The first trackable version this issue affected is Minecraft 1.4.2*
The four legs of a sheep and its outer wool cannot be independently retextured from one another, making them always look the same. This is limiting to the player's resource pack creativity and freedom to edit the texture.

Steps to Reproduce:

1. Download and apply the following resource pack:
   Sheep.zip
2. Spawn/Summon a sheep

Observed Behavior:

All four legs of the sheep will look entirely red (with the outer wool layer being blue), despite the player seemingly only modifying one leg in the UV map.

Expected Result:

Only one of the legs 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:

1. Related independent retexture issues:
   MC-274259 MC-274254 MC-274251 MC-274250 MC-274249 MC-274247 MC-274246 MC-274197 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 MC-271770 MC-271773 MC-271780 MC-271982 MC-271988 MC-271989 MC-271990 MC-271992 MC-271993
2. Also related to MC-242398