Custom Field Choice Set: Duplicate values result in missing options in Selection field UI

[Mister-MAP]

NetBox Edition

NetBox Community

NetBox Version

v4.4.8

Python Version

3.12

Steps to Reproduce

1. Go to Customization > Custom Field Choices.
2. Create a new Choice Set (e.g., "Region").
3. In the Extra Choices add the following entries with duplicate values:
   dc1:Asia
   dc1:Europe
   dc2:America
4. Save the Custom Field Choice Set (System accepts this without error).
5. Go to Customization > Custom Fields.
6. Create a new field:

• Name: "Region"
• Type: Selection
• Choice Set: "Region"

• Object Types: IPAM > VLAN (or any other object)

7. Navigate to IPAM > VLANs and click Add.
8. Try to select a value in the newly created custom field (there will be only one entry with dc1 value).

Expected Behavior

Scenario A (Likely intended): NetBox should prevent saving the Choice Set if duplicate values exist, raising a validation error (e.g., "Values must be unique").
Scenario B (Preferable for my case): If duplicate values are permitted, the dropdown UI should display both "Asia" and "Europe" as distinct selectable options.

Observed Behavior

1. The Choice Set is saved successfully with duplicate values.
2. In the VLAN creation form, the dropdown list shows:

• Asia (value: dc1)
• America (value: dc2)

3. The option Europe (value: dc1) is missing from the list.

It seems the UI de-duplicates options based on the value key.

[jeremystretch]

The intended behavior is that a choice set should not permit duplicate choice values.