Cannot delete hundreds of duplicate contacts I have a Google account and a MS Exchange account (Outlook). There are multiple instances of hundreds of duplicate contacts for a single name; e.g. John Smith. They are in "not assigned" groups. If i go into contacts and delete all 200-400 of them, they all reappear in a couple of hours. 

They take up so much space; there are thousands of them.

I very much appreciate your help and ideas.

I"m using a Galaxy S3, v4.4.2.
Firstly where are the duplicates from? You should be able to selectively sync items from exchange, thus uncheck the contacts section. Furthermore, some default contact apps allow "link", where you can link all aspects of the contacts. I gather your issue is for phone, mobile, email etc it is creating another contact. 

The fact that they are reappearing backs the theory it is due to repeated sync. A handy alternative would be grab any contacts from your exchange, tick the option to migrate to SIM then disable sync. You'll still be able to search for them via email etc by selecting "search on server" etc.