deleting duplicate contacts on iPhone5, iOS 7

Hi

I have an iPhone5 which is on iOS7 +; legit, no jailbreak.

Say 20 ~ 30% of the contacts are duplicates. Rest of the contacts are unique

I wish to delete *only* the duplicate contacts

Is there a way to delete duplicates WITHOUT locating each such duplicate and manually deleting it on iPhone ? i.e. some smart way ?

I have already backed up contacts to a g mail account , but alas do NOT know how to do a 100% synch and delete duplicates

any help including other ideas would be appreciated


Thanks in adv
Regards
Subu