To reproduce:

1. Build a radio field with 3 options
2. Save and re-open the dialog
3. Edit the radio field and add a 4th option
4. Delete one of the first 3 options
5. Add a new option

The new option from step 5 is assigned the same ID as the item added in step 3.

Related: 9d9e854, 5064129, and 10f36b2.