I had to restore my iTunes Folder and all its contents from a Time Machine backup, but now Time Machine wants to back it all up again fully, all 75 GBs of it which I just got from TM to begin with! What strategies can I use to save some space? Delete the older backup (although I don't think the older backup has all the files in one place)?
When you restore something then the contents of your hard drive have changed. TM will then backup what has changed. There's nothing abnormal about what's happening. If you want to save space use the TM application to delete the iTunes folder you restored. Then you will only have one copy - the most recent one.