Q: How do I delete duplicate contacts in iCloud?  All contacts have a duplicate.

I have a rather large contact file organized in groups. When I open Contacts in iCloud.com each contact appears twice.  How do I easily delete the duplicates and how can I avoid getting duplicates the next time I sync?  Should I delete all my contacts in iCloud Contacts?  How?  My iPhone shows the same contacts but no duplicates.  I'm nervous that the next time I sync I will get NO contacts on all my devices.  I do have original contact list on my PC in 2003 Outlook.