A long time ago I backed up my contacts to iCloud and got a bunch of duplicates.

[aliensarecool]

Is that common? Afraid to try again

 

[r2shyyou]

Is that common? Afraid to try again

I'd say yes, it's pretty common.

If you do decide to back them up to iCloud again, below are some hopefully helpful links in the event that you find duplicates:

Apple Support document: iCloud: Resolving duplicate Contacts after setting up iCloud Contacts
Previous, related MacRumors thread: Duplicate Contacts in address book with iCloud
OS X Daily article (if you have a Mac): Merge & Clear Duplicate Contacts from Address Book and iPhone