Aliasing poses → multiple_poses
Link to alias

Reason:

Same.

Multiple poses is used for single characters that are shown in various poses. Most commonly seen on model sheets.

Poses is used in the same way. It's currently empty, but that's just because I've cleaned it up. There's occasional new images tagged with poses, so I think those should be aliased.

Why not alias both to pose?

I can see implicating multiple_poses to pose, but why alias? I don't think it's redundant, or at least I can't think of any other tag for multi-pose images such as...:
post #68534 post #75134

I would agree with aliasing multiple_poses to pose if we were to alias one