Managing 2 iphone/iTunes accounts on one computer

Question

Me an my wife both have iPhones. Each one is currently managed on separate profiles on our Macbook. This was fine to begin with, but now it's killing memory on the computer by having many of the same exact songs taking up memory twice (what would be a 7GB library is now a 14GB one).
Is there a way to have our iPhones sync on one side of the Mac (while maintaining individual account info for the iTunes store) as to avoid keeping double music files?

Answer 1

Try this...
Quit iTunes.
Drag your entire iTunes folder from /Username/Music to /Users/Shared.
Log out.
Log in on your Wife's account.
Click on the iTunes icon to start it, then immediately press an hold the Option key.
iTunes will ask to Create new library or Choose existing library. Select Choose existing library.
Select the iTunes library file in the iTunes folder in /Users/Shared.
iTunes will open and all the music in your account will be there.
Now, go to iTunes prefs -> Advanced -> Importing.
Make sure Copy files to iTunes music folder when adding to library is ticked.
If your wife currently has ALL the same music as you, do not do this step. It will simply add all the music again and you will have duplicates of everything. If she has some different than you, you will have to select those artists/songs specifically.
Go to File -> Add to library and select the iTunes music folder (or only the individual artists/albums/songs that you do not have) in /Wife's username/Music/iTunes. This will add all the music in her account.
When done, quit iTunes.
Go to /Wife's username/Music and drag the iTunes folder to the trash. Do NOT empty the trash yet.
Restart iTunes normally (don't hold Option).
Everything should be there.
Quit iTunes and log out of her account.
Log into your account, start iTunes normally and all music should bet there.
Quit iTunes and go back into her account and make sure iTunes works okay. If it does, empty the trash.