diff --git a/python/GafferUITest/SpreadsheetUITest.py b/python/GafferUITest/SpreadsheetUITest.py
index ff6878d53f4..821719145b1 100644
--- a/python/GafferUITest/SpreadsheetUITest.py
+++ b/python/GafferUITest/SpreadsheetUITest.py
@@ -884,5 +884,35 @@ def testRowMetadataNotPromotedRedundantly( self ) :
 		for plug in Gaffer.Plug.RecursiveRange( promoted[1] ) :
 			self.assertEqual( Gaffer.Metadata.registeredValues( plug, Gaffer.Metadata.RegistrationTypes.Instance ), [] )
 
+	def testMetadataAlgoRemovesNonDefaultRowMetadata( self ) :
+
+		spreadsheet = Gaffer.Spreadsheet()
+		spreadsheet["rows"].addColumn( Gaffer.StringPlug( "column1" ) )
+		spreadsheet["rows"].addRows( 1 )
+
+		# Create Spreadsheet where non-default row has its own metadata that conflicts with the values
+		# that should be mirrored from the default row. It used to be possible for the user to get into
+		# this situation because we redundantly promoted metadata onto the non-default rows.
+
+		Gaffer.Metadata.registerValue( spreadsheet["rows"][0]["cells"][0], "spreadsheet:columnWidth", 100 )
+		Gaffer.Metadata.registerValue( spreadsheet["rows"][1]["cells"][0], "spreadsheet:columnWidth", 200 )
+		Gaffer.Metadata.registerValue( spreadsheet["rows"][0]["cells"][0], "spreadsheet:columnLabel", "Label 1" )
+		Gaffer.Metadata.registerValue( spreadsheet["rows"][1]["cells"][0], "spreadsheet:columnLabel", "Label 2" )
+
+		# Even though the non-default-row values are different to the default row ones, we still want
+		# `deregisterRedundantValues()` to clean them up, because having different column widths/labels
+		# on different rows is logically impossible.
+
+		Gaffer.MetadataAlgo.deregisterRedundantValues( spreadsheet["rows"] )
+
+		for row in spreadsheet["rows"] :
+			self.assertEqual( Gaffer.Metadata.value( row["cells"][0], "spreadsheet:columnWidth" ), 100 )
+			self.assertEqual( Gaffer.Metadata.value( row["cells"][0], "spreadsheet:columnLabel" ), "Label 1" )
+
+		self.assertEqual(
+			Gaffer.Metadata.registeredValues( spreadsheet["rows"][1]["cells"][0], Gaffer.Metadata.RegistrationTypes.Instance ),
+			[]
+		)
+
 if __name__ == "__main__":
 	unittest.main()
diff --git a/src/Gaffer/MetadataAlgo.cpp b/src/Gaffer/MetadataAlgo.cpp
index 9e901bd8c7e..1536064970d 100644
--- a/src/Gaffer/MetadataAlgo.cpp
+++ b/src/Gaffer/MetadataAlgo.cpp
@@ -42,6 +42,7 @@
 #include "Gaffer/Plug.h"
 #include "Gaffer/Reference.h"
 #include "Gaffer/ScriptNode.h"
+#include "Gaffer/Spreadsheet.h"
 
 #include "IECore/SimpleTypedData.h"
 
@@ -62,6 +63,8 @@ IECore::InternedString g_connectionColorKey( "connectionGadget:color" );
 IECore::InternedString g_noduleColorKey( "nodule:color" );
 const std::string g_annotationPrefix( "annotation:" );
 const InternedString g_annotations( "annotations" );
+const InternedString g_spreadsheetColumnWidth( "spreadsheet:columnWidth" );
+const InternedString g_spreadsheetColumnLabel( "spreadsheet:columnLabel" );
 
 void copy( const Gaffer::GraphComponent *src , Gaffer::GraphComponent *dst , IECore::InternedString key , bool overwrite )
 {
@@ -769,6 +772,23 @@ void deregisterRedundantValues( GraphComponent *graphComponent )
 			// back to an identical value.
 			Gaffer::Metadata::deregisterValue( graphComponent, key );
 		}
+
+		// Special-case for badly promoted spreadsheet metadata of old.
+		if( key == g_spreadsheetColumnWidth || key == g_spreadsheetColumnLabel )
+		{
+			if( auto row = graphComponent->ancestor<Spreadsheet::RowPlug>() )
+			{
+				if( auto rows = row->parent<Spreadsheet::RowsPlug>() )
+				{
+					if( row != rows->defaultRow() )
+					{
+						// Override on non-default row doesn't agree with the value
+						// that should be mirrored from the default row. Remove it.
+						Gaffer::Metadata::deregisterValue( graphComponent, key );
+					}
+				}
+			}
+		}
 	}
 
 	for( auto &child : GraphComponent::Range( *graphComponent ) )