diff --git a/e2e/tests-dfx/cycles-ledger.bash b/e2e/tests-dfx/cycles-ledger.bash
index 84c401d244..3bfe2316d3 100644
--- a/e2e/tests-dfx/cycles-ledger.bash
+++ b/e2e/tests-dfx/cycles-ledger.bash
@@ -25,7 +25,11 @@ teardown() {
     standard_teardown
 }
 
-@test "cycles ledger balance" {
+current_time_nanoseconds() {
+  echo "$(date +%s)"000000000
+}
+
+@test "balance" {
     ALICE=$(dfx identity get-principal --identity alice)
     ALICE_SUBACCT1="000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f"
     ALICE_SUBACCT1_CANDID="\00\01\02\03\04\05\06\07\08\09\0a\0b\0c\0d\0e\0f\10\11\12\13\14\15\16\17\18\19\1a\1b\1c\1d\1e\1f"
@@ -99,9 +103,7 @@ teardown() {
     assert_eq "2.900 TC (trillion cycles)."
 }
 
-@test "cycles ledger transfer" {
-    copy_cycles_ledger
-
+@test "transfer" {
     ALICE=$(dfx identity get-principal --identity alice)
     ALICE_SUBACCT1="000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f"
     ALICE_SUBACCT1_CANDID="\00\01\02\03\04\05\06\07\08\09\0a\0b\0c\0d\0e\0f\10\11\12\13\14\15\16\17\18\19\1a\1b\1c\1d\1e\1f"
@@ -113,9 +115,9 @@ teardown() {
     assert_command dfx deploy cycles-ledger
     assert_command dfx deploy cycles-depositor --argument "(record {ledger_id = principal \"$(dfx canister id cycles-ledger)\"})" --with-cycles 10000000000000
 
-    assert_command dfx canister call cycles-depositor deposit "(record {to = record{owner = principal \"$ALICE\";};cycles = 3_000_000_000_000;})" --identity icp-giver
-    assert_command dfx canister call cycles-depositor deposit "(record {to = record{owner = principal \"$ALICE\"; subaccount = opt blob \"$ALICE_SUBACCT1_CANDID\"};cycles = 2_000_000_000_000;})" --identity icp-giver
-    assert_command dfx canister call cycles-depositor deposit "(record {to = record{owner = principal \"$ALICE\"; subaccount = opt blob \"$ALICE_SUBACCT2_CANDID\"};cycles = 1_000_000_000_000;})" --identity icp-giver
+    assert_command dfx canister call cycles-depositor deposit "(record {to = record{owner = principal \"$ALICE\";};cycles = 3_000_000_000_000;})" --identity cycle-giver
+    assert_command dfx canister call cycles-depositor deposit "(record {to = record{owner = principal \"$ALICE\"; subaccount = opt blob \"$ALICE_SUBACCT1_CANDID\"};cycles = 2_000_000_000_000;})" --identity cycle-giver
+    assert_command dfx canister call cycles-depositor deposit "(record {to = record{owner = principal \"$ALICE\"; subaccount = opt blob \"$ALICE_SUBACCT2_CANDID\"};cycles = 1_000_000_000_000;})" --identity cycle-giver
 
     # account to account
     assert_command dfx cycles balance --cycles-ledger-canister-id "$(dfx canister id cycles-ledger)" --precise --identity alice
@@ -123,9 +125,8 @@ teardown() {
     assert_command dfx cycles balance --cycles-ledger-canister-id "$(dfx canister id cycles-ledger)" --precise --identity bob
     assert_eq "0 cycles."
 
-    # assert_command dfx canister call cycles-ledger icrc1_transfer "(record {to = record{owner = principal \"$BOB\"}; amount = 100_000;})" --identity alice
     assert_command dfx cycles transfer 100000 --cycles-ledger-canister-id "$(dfx canister id cycles-ledger)" --identity alice --to-owner "$BOB"
-    # assert_eq "(variant { Ok = 3 : nat })"
+    assert_eq "Transfer sent at block index 3"
 
     assert_command dfx cycles balance --cycles-ledger-canister-id "$(dfx canister id cycles-ledger)" --precise --identity alice
     assert_eq "2999899900000 cycles."
@@ -139,9 +140,8 @@ teardown() {
     assert_command dfx cycles balance --cycles-ledger-canister-id "$(dfx canister id cycles-ledger)" --precise --identity bob --subaccount "$BOB_SUBACCT1"
     assert_eq "0 cycles."
 
-    # assert_command dfx canister call cycles-ledger icrc1_transfer "(record {to = record{owner = principal \"$BOB\"}; amount = 100_000;})" --identity alice
     assert_command dfx cycles transfer 100000 --cycles-ledger-canister-id "$(dfx canister id cycles-ledger)" --identity alice --to-owner "$BOB" --to-subaccount "$BOB_SUBACCT1"
-    # assert_eq "(variant { Ok = 3 : nat })"
+    assert_eq "Transfer sent at block index 4"
 
     assert_command dfx cycles balance --cycles-ledger-canister-id "$(dfx canister id cycles-ledger)" --precise --identity alice
     assert_eq "2999799800000 cycles."
@@ -172,8 +172,8 @@ teardown() {
     assert_command dfx cycles balance --cycles-ledger-canister-id "$(dfx canister id cycles-ledger)" --precise --identity bob --subaccount "$BOB_SUBACCT1"
     assert_eq "100000 cycles."
 
-    # assert_command dfx canister call cycles-ledger icrc1_transfer "(record {to = record{owner = principal \"$BOB\"}; amount = 100_000;})" --identity alice
     assert_command dfx cycles transfer 400000 --cycles-ledger-canister-id "$(dfx canister id cycles-ledger)" --identity alice --to-owner "$BOB" --to-subaccount "$BOB_SUBACCT1" --from-subaccount "$ALICE_SUBACCT2"
+    assert_eq "Transfer sent at block index 6"
 
     assert_command dfx cycles balance --cycles-ledger-canister-id "$(dfx canister id cycles-ledger)" --precise --identity alice --subaccount "$ALICE_SUBACCT2"
     assert_eq "999798900000 cycles."
@@ -182,7 +182,65 @@ teardown() {
     assert_eq "500000 cycles."
 }
 
-@test "cycles ledger howto" {
+@test "transfer deduplication" {
+    ALICE=$(dfx identity get-principal --identity alice)
+    BOB=$(dfx identity get-principal --identity bob)
+
+    assert_command dfx deploy cycles-ledger
+    assert_command dfx deploy cycles-depositor --argument "(record {ledger_id = principal \"$(dfx canister id cycles-ledger)\"})" --with-cycles 10000000000000
+
+    assert_command dfx canister call cycles-depositor deposit "(record {to = record{owner = principal \"$ALICE\";};cycles = 3_000_000_000_000;})" --identity cycle-giver
+
+    assert_command dfx cycles balance  --precise --identity alice --cycles-ledger-canister-id "$(dfx canister id cycles-ledger)"
+    assert_eq "3000000000000 cycles."
+
+    assert_command dfx cycles balance --precise --identity bob --cycles-ledger-canister-id "$(dfx canister id cycles-ledger)"
+    assert_eq "0 cycles."
+
+    t=$(current_time_nanoseconds)
+
+    assert_command dfx cycles transfer 100000 --created-at-time "$t" --memo 1 --identity alice --to-owner "$BOB" --cycles-ledger-canister-id "$(dfx canister id cycles-ledger)"
+    assert_eq "Transfer sent at block index 1"
+
+    assert_command dfx cycles balance --precise --identity alice --cycles-ledger-canister-id "$(dfx canister id cycles-ledger)"
+    assert_eq "2999899900000 cycles."
+
+    assert_command dfx cycles balance --precise --identity bob --cycles-ledger-canister-id "$(dfx canister id cycles-ledger)"
+    assert_eq "100000 cycles."
+
+    # same memo and created-at-time: dupe
+    assert_command dfx cycles transfer 100000 --created-at-time "$t" --memo 1 --identity alice --to-owner "$BOB" --cycles-ledger-canister-id "$(dfx canister id cycles-ledger)"
+    assert_contains "transaction is a duplicate of another transaction in block 1"
+    assert_contains "Transfer sent at block index 1"
+
+    assert_command dfx cycles balance --precise --identity alice --cycles-ledger-canister-id "$(dfx canister id cycles-ledger)"
+    assert_eq "2999899900000 cycles."
+
+    assert_command dfx cycles balance --precise --identity bob --cycles-ledger-canister-id "$(dfx canister id cycles-ledger)"
+    assert_eq "100000 cycles."
+
+    # different memo and same created-at-time same: not dupe
+    assert_command dfx cycles transfer 100000 --created-at-time "$t" --memo 2 --identity alice --to-owner "$BOB" --cycles-ledger-canister-id "$(dfx canister id cycles-ledger)"
+    assert_contains "Transfer sent at block index 2"
+
+    assert_command dfx cycles balance --precise --identity alice --cycles-ledger-canister-id "$(dfx canister id cycles-ledger)"
+    assert_eq "2999799800000 cycles."
+
+    assert_command dfx cycles balance --precise --identity bob --cycles-ledger-canister-id "$(dfx canister id cycles-ledger)"
+    assert_eq "200000 cycles."
+
+    # same memo and different created-at-time same: not dupe
+    assert_command dfx cycles transfer 100000 --created-at-time $((t+1)) --memo 1 --identity alice --to-owner "$BOB" --cycles-ledger-canister-id "$(dfx canister id cycles-ledger)"
+    assert_contains "Transfer sent at block index 3"
+
+    assert_command dfx cycles balance --precise --identity alice --cycles-ledger-canister-id "$(dfx canister id cycles-ledger)"
+    assert_eq "2999699700000 cycles."
+
+    assert_command dfx cycles balance --precise --identity bob --cycles-ledger-canister-id "$(dfx canister id cycles-ledger)"
+    assert_eq "300000 cycles."
+}
+
+@test "howto" {
     # This is the equivalent of https://www.notion.so/dfinityorg/How-to-install-and-test-the-cycles-ledger-521c9f3c410f4a438514a03e35464299
     ALICE=$(dfx identity get-principal --identity alice)
     BOB=$(dfx identity get-principal --identity bob)
diff --git a/src/dfx/src/commands/cycles/transfer.rs b/src/dfx/src/commands/cycles/transfer.rs
index 3b2f5fb756..384ebed8d6 100644
--- a/src/dfx/src/commands/cycles/transfer.rs
+++ b/src/dfx/src/commands/cycles/transfer.rs
@@ -31,7 +31,8 @@ pub struct TransferOpts {
     #[arg(long, requires("to_owner"))]
     to_subaccount: Option<Subaccount>,
 
-    /// Transaction timestamp, in nanoseconds, for use in controlling transaction-deduplication, default is system-time. // https://internetcomputer.org/docs/current/developer-docs/integrations/icrc-1/#transaction-deduplication-
+    /// Transaction timestamp, in nanoseconds, for use in controlling transaction-deduplication, default is system-time.
+    /// https://internetcomputer.org/docs/current/developer-docs/integrations/icrc-1/#transaction-deduplication-
     #[arg(long)]
     created_at_time: Option<u64>,