Duplicating field with select options results in two fields sharing same underlying options

How to reproduce:

1. Create a single select field
2. Fill it with options, make sure some cells are using those options
3. Duplicate the single select field
4. Edit the first single select field
5. Remove an option that appears in cells in both the original and duplicate and save
6. Notice that both the original AND duplicate fields have that option removed
7. Only the field being editted should have that single select option removed