If you make a copy of a global color the new color will have the exact same name as the original. This causes all sorts of problems since no two swatches should have the same name.
Steps to reproduce:
Create a new global color in the Swatches panel, notice the name
Right click it and choose Make Copy
Check the name of the new global color, it's the exact same as the original
Strangely, this does not happen to regular colors. If you make a copy of a regular color the app will always change the copy's name.
Thanks!