I don't keep the neatest office/desk area in the world. There is some stuff I bring home that I have to save for a while - when the need passes, I just stack them close at hand and out of the way. Plus, I don't always think of doing this, but when I do there's almost always a small stack available..
I presume running fused copies through the process again will not effect the printing mechanism in any way. After all, that's what duplexing (manual or automatic) does, so it shouldn't bother it at all