On one of my Macs the contacts are duplicated

Change the view (in Contacts) from All Contacts to All iCloud.

I would LOVE to do this, as I have the exact same problem: duplicates of every group I've made and dupes of every contact on my iMac: 1. On my Mac (which I'd love to hide) and 2. iCloud (my choice to keep).

However, in the View menu, my only choices are: Groups, List and Card, or Card Only, and only affects what I see in the UI. No ability to choose All iCloud, as you mention.

I've gone into Prefs and see no option there, either. I've made iCloud my default account, but that didn't change anything.

Thanks for pointing me in the non-dupe direction. This has been a PITA.

Select the groups view from the view menu, select the 3 page option from the buttons on the bottom right of the lefthand page:

Then look here.

Brilliant! Thanks, poof, and the dupes are not visibile now!

Ah, but another wrinkle, yet to be ironed out.

I use Mail's capture of addresses feature all the time, to add new clients to Address Book. I just added one before moving to this All iCloud view, and she's not showing up now! Some other pref I have to make in Mail, perhaps? She's still there in All Contacts view…

Yes indeed there are more preferences.

Addresses are sent to the default database, in your case I'll guess that On My Mac is the default, here's how to change that.

Contacts>Preferences>General

Likely that's it. I only changed it AFTER I'd added my latest client. Thanks.

You're welcome.

****. Not quite over, looks like.

I'm in the 3 panel view, I've selected All iCloud, and I still see duped groups:

Please take a screenshot and post it here.