Need help understanding all of this... A husband and wife want to share their music libraries. He has a PC, she has a Mac. He has his own iTunes account, call it "email@example.com" and an iPhone. She has her own iTunes account, call it "firstname.lastname@example.org" and an iPhone. I figured Home Sharing would be an excellent fit. So I authorized his computer using her iTunes account - i.e. in iTunes I chose Store - Authorize Computer and entered "email@example.com" and her password. I was told that it was successful and that she had used 3 of her 5 available authorizations. Home Sharing worked great. Then I became concerned that when "he" got home and synced his iPhone it might mess up his apps because he had purchased them using the "firstname.lastname@example.org" iTunes account, and his computer was now authorized with the "email@example.com" iTunes account. After much discussion about which iTunes account would be the one they'd use, we decided that we'd put them back to each having their own after transferring the music. (99% of their music is CD rips, so the iTunes DRM really not an issue) Then I noticed that in iTunes under Store it says next to View My Account: "firstname.lastname@example.org" ! I thought I had changed his computer to "email@example.com". I didn't deauthorize him first. So, the only explanation I can come up with is that his computer is authorized for two iTunes accounts - "firstname.lastname@example.org" and "email@example.com". I was not aware that you could be authorized to more than one iTunes Store accounts. I guess you can? Again, the main goal was to share their music libraries, while at the same time not messing up iPhone apps.