"Copy Value From Other Field" Post Function does not show all Custom Fields with Same Name When Selecting From Dropdown Box

Steps to reproduce:
1. Create three custom fields with the same name and different type. Screen1BUGREPORT.jpg
2. Go to any workflow transition and add a new POST FUNCTION, of type Copy Value From Other Field function.
3. Only one of the three created custom fields is shown. Screen2BUGREPORT.jpg