You're at least the seventh person I've seen with the same bug. Based on the response I got from SM it could be implied that at this point, double-clicking a material collection in the pose room shouldn't really be working for anyone.

You can see SM's response in the thread I started here;
http://www.renderosity.com/mod/forumpro/showthread.php?thread_id=2779136

It's toward the bottom.