[BUG] Applying Mount Twice Locks Token Size

[Sniperfox47]

Describe the bug
Applying mount a second time on a resized mounter while already mounted causes the token to lock into that size.

For example if you have two medium sized targets selected and click mount twice, the mounter will be locked to half size even after clicking dismount, until you go fix it manually.

Environment Details
Foundry VTT Version: 0.6.1
Mount Up! Version: 3.0.1

To Reproduce
Steps to reproduce the behavior:
_1. Select two tokens of the same size and click mount
2. Click mount a second time while already mounted/resized.
3. Click unmount and notice the resized token does not return to original size

Expected behavior
Token remembers original size and does not get overwritten while already mounted. Ideally should throw a "cannot mount" error like it does with trying to mount a new target while already mounted.

Screenshots
Original Size:

After clicking mount twice:

After dismounting: