Hello, do you want to see multiple animations at the same time or do you want to see multiple skins at the same time?
I will assume you want this for reference purposes.
Likely, the easiest way to have the same character perform two different animations or the same animation with a different skin is to select the skeleton in the tree hierarchy, duplicate the skeleton, then have the duplicate skeleton display the animation and skin you want to use as reference.
After you are done, you can delete the skeleton.