Problem with mp3's - multiple Itunes collections

I have 2 different ITunes libraries saved on my hard drive, one is mine and the other my girlfriends. There are a bunch of albums that appear in both libraries, so when I play one in the media player (gen2), it plays each song twice. Is there a way to fix this? It’s annoying to have to skip each repeated song and I want to keep the backed up libraries the way they are (I’m not going to delete the doubled albums from her library).

Also, when scrolling through the mp3 libraries (about 80 gb total) it takes FOREVER to get to the end of the list. Is there a way to make it browse faster? It takes several minutes to get to albums beginning with “The.”

I like the player overall, but the user interface leaves A LOT to be desired.