Steps to reproduce:

1. Have 2 accounts saved in the launcher.
2. Open the launcher on account A, select the skin view.
3. Switch Account to account B.
4. Select the skin view.

The skin of Account A is shown instead of B. Upon exiting and opening the launcher, the correct skin is shown.

(might be because the launcher caches the skin and incorrectly loads the cached skin, if this is the case, a simple fix would be to save the cached skin using the UUID of the user, this way you ensure the right cache is used.)