Enable "On My Mac" Contacts
bmike's work around did not quite do it for me as, as soon as I re-enabled iCloud everything was merged back into one bunch of iCloud contacts again.

What did work for me is very similar though:


Select one or more of your contacts from the iCLouds group and drag them to your desktop creating one vCard.
In Preference > Accounts > iCloud uncheck the "Enable this Account". "On My Mac" appears immediately in the Group pane.
Drag the vCard from your desktop over the empty contact space, your contacts will be imported in "On My Mac".
In Preference > Accounts > iCloud check the "Enable this Account". iCloud will reappear as Group.


You now have two sets of contacts, one "On My Mac" and one "All iCloud". If you started out by dragging all contacts in the iCloud group to your desktop the two sets will be completely identical. Does it make sense to do that? Well, you'll always have your contacts available also in the event that your network is down. Furthermore it is a way of making a back-up of your iCloud contacts alternative to what is proposed on:

Archive or make copies of your iCloud data:
http://support.apple.com/kb/HT4910?viewlocale=en_US&amp;locale=en_US

Edit August 25

In addition to my answer fo August 20 I stumbled over perhaps an even better way of making an exact copy of your contacts from iCloud to your Mac. Once you have re-enabled iCloud you can select all contacts in "All iCloud" and just drag them in your "All on my Mac" group, so without using the back up you made earlier to your desktop. The nice thing is that your contacts birthdays won't show up twice in your Mac Calendar as they do when copied via Desktop first. Any contacts you add or delete via iCloud won't show up on or disappear from your On My Mac version. Editing of the content in iCloud appears to affect the On my Mac content as well when it is done in the Mac Contact app, not if it is done in iCloud on any other device. Anyway, the Contact App on your Mac distinguishes nicely the differences between the two. Just try it out by typing something in the Note field in either Group in Mac Contact or in your web based iCloud.