I just upgraded to a new MacBook Pro and moved my Media Center 24 library to an external hard drive. Now, I have every song/album in double. Does anyone know how to resolve this?
It sounds like you externally copied your music files to an external drive and then told MC to use that as an Auto Import location.
The general way to move music files en-masse with MC is this (might be missing some detail here and there):
1. Make a library backup with File > Library > backup library
2. Turn off auto import
3. Shut down MC.
4. Move your files externally with whatever tool you like. This will probably take a long time.
5. Fire MC back up and see that all of your files are now "broken" because MC thinks they are on the OLD drive, but they are not. You moved them.
6. Use the Rename, Move, and Copy files tool. Use the "update database location" action. This will tell MC, for each file, "hey, I moved that file over here". You probably want to uncheck "Directories" and "Filename", and instead check "Find & Replace". In the Find & Replace parameters, you want to substitute the old location with the new location. This will probably be something like /Volumes/Macintosh Hard Drive/ and /Volumes/Big_External_Drive/ .
For this last step, go slow. Do one song and see if it works. If not, try again. Once you get a song to work, do an album. Once that works, do a more albums. Eventually select everything and do those too.
If you screw it up too badly you can just restore from the backup you made in step #1.
This probably seems really involved. It's detailed, but it's really not bad. I've done it dozens of times and had very very few problems. It's just a matter of understanding the process and experimenting a little bit.
Use the Preview area in the Rename Move and Copy files Tool! It's your friend. It will show you what it's going to do before it does it.
Good luck.
Brian.