(This issue first appeared in Minecraft Beta 1.8 Pre-release 1, but as that cannot be added as an affected version, the earliest would be Minecraft 1.4.2)
The right/left arms and legs of an enderman cannot be independently rextured from one another at all, making all four limbs always look the same. All four limbs share the same section on the UV map, meaning both arms and legs cannot be unique to eachother, and the right/left arm/leg cannot be unique to one another. This limits resource pack creativity, and is not resource pack friendly.

Steps to Reproduce:

1. Download and apply the following resource pack:
   Enderman.zip
2. Spawn an enderman

Observed Behavior:

The enderman's arms and legs will all look the same (entirely red), despite the player seemingly only modifying one arm or leg in the UV map.

Expected Result:

Only one of the enderman's arms or 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. This notably affects the "eyes" overlay as well, considering it shares the same UV map as the base texture.
2. 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 MC-271770 MC-271773
3. Related enderman texture issues:
   MC-123742