The other day I noticed that my contacts where duplicated by Waze (on Android). This describes how to fix it and easily remove the duplicates.
It turned out that Waze adds an account under Android Settings→Accounts and turns on synchronization and that this is what causes this. In order to remove all “Waze contacts” from the address book, go to Settings→Accounts→Waze and turn off synchronization. Also choose delete account. Resync Google contacts and voila, your address book should be in order again.
N.B. you will still be logged in to your account in Waze, so no need to worry about that.
Thanks to the Waze forum for clearing this out.
P.S. While you’re here, take a look at Resurrecting the MacBook Air on why putting computer parts in the kitchen oven sometimes actually can do good.