iTunes Cloud Music Library Duplicates Everything on one Mac, times out on another

I have two Macs, a MacBook Air (on which I removed all music for this purpose) and an iMac which contains nearly 58,000 songs.

After learning the 25,000 song cap was lifted with the new iTunes/iOS, I signed up for both Apple Music and iTunes Match.

After activating it on the MacBook Air, I see that, in the Cloud, nearly every single song listed is posted twice. This goes for the several thousand purchased ones and the ones listed as "Waiting ..." . More on that next. When I hit Show Duplicates and Same Album I see some 40,000 duplicated songs. I can't remove half of those manually.

AND ...

On the iMac with the 57,000 songs, I was able to add the computer to iTunes Match, but when it goes to get the information about my music library, the wheel spins and spins and eventually returns with ...

Genius results can’t be updated right now. An unknown error occurred (4010).

This has been going on for three days now. And, as a result, I am unable to make use of the iTunes Match I've paid for and the offline use of Apple Music as i expect to pay for in three months.

Can ANYONE help? Three calls to AppleCare have produced exactly zero.