Mutating into a Beast keeps swapping between Animal Discord and Terrifying

[edwardspec]

Describe the bug

Beast mutation has 2 different mutations in ANIMAL_EMPATHY category, and neither of them prevents another from developing. They keep mutating back and forth (Animal Discord can be replaced by Terrifying, and Terrifying can be replaced by Animal Discord).

https://cdda-guide.nornagon.net/mutation_type/ANIMAL_EMPATHY
https://cdda-guide.nornagon.net/mutation_category/BEAST

Attach save file

N/A

Steps to reproduce

1. In debug, add all BEAST mutations to yourself except Animal Discord.
2. Eat some beast mutagen.
3. Wait for new mutations. It will mutate Animal Discord, then Terrifying, then Animal Discord, then Terrifying...

Expected behavior

One of these 2 mutations should prevent another from developing.

Screenshots

No response

Versions and configuration

Applicable to both 0.I and latest experimental.

Additional context

No response