The right and left fins of a dolphin cannot be independently retextured

The right and left fins of a dolphin cannot be independently retextured from one another, making them always look the same, limiting the player's resource pack creativity.

Steps to Reproduce:

1. Download and apply the following resource pack:
   Dolphin.zip
2. Spawn a dolphin

Observed Behavior:

Both fins of the dolphin will look entirely red, despite the player seemingly only modifying one fin in the UV map.

Expected Result:

Only one of the fins would be altered, since that is what the player intended to change. The current behavior is unexpected and not resource pack friendly.

Screenshots/Videos:

Notes:

Related independent retexture issues:
MC-271355 MC-271384 MC-271383 MC-271368 MC-271363 MC-271357 MC-271355 MC-271354 MC-271330 MC-271305 MC-271304 MC-271232 MC-264571 MC-270516 MC-270517 MC-145334 MC-265343 MC-265345 MC-270530 MC-271767 MC-271768 MC-271769