Transfer of tracks from iTunes to Music; deleting duplicates

My 10 year old Mac Pro recently died. I had a lot of music on it (300 albums) in iTunes which was backed up to an external drive as part of a time machine back-up. An Apple technician helped me transfer the files from the itunes files to my new iMac into the new Music program, and to get the files onto my iphone.

When I looked at the files the next day, almost every album had duplicate tracks. I was able to figure out how to view all of the duplicates, but I could not figure out a way to delete all of the duplicates at one time. I called Apple and spoke to a technician who told me that there was no way to delete all the duplicates at once. They said each file had to be selected and deleted individually. Is Apple really this lame, or is there a way to do this that isn't obvious?