Porting iTunes library to new iMac: error -8084

I'm setting up a new iMac - and I started by copying over my iTunes library from my Mac mini via WiFi. The copy kicked off without a hiccup - and it ran for 6+ hours. This morning, I checked the progress and it showed that the operation can't be completed because an unexpected error occurred (error code -8084).

I see that means that there was an error on the disk (I presume it's the originating disk). However, I saw that the iTunes library on my new machine is loaded with lots of files - so I fired up iTunes. I created a new smart playlist for all my songs and I show more than double the song count on my new machine than in the same playlist on the original machine.

I looked at iTunes to see if there was a duplicate for each song, and that does not appear to be the case. I also don't have any Podcasts on the new machine yet that would account for additional items in the library.

Any suggestions for how to proceed? I don't want to lose the music I have - but I also want to avoid having to manually update the whole library.

Many thanks in advance for your thoughtful input.