how to merge duplicate contacts in icloud ?

Hello, Gurleen7.

Thank you for visiting Apple Support Communities.

Here is a troubleshooting article I would recommend when experiencing issues with duplicate iCloud data.

iCloud: Resolving duplicate Contacts after setting up iCloud Contacts

http://support.apple.com/kb/TS4147

Before processing any troubleshooting steps make sure to backup your data. See the section referring to contacts in the article below.

iCloud: Archiving or making copies of your iCloud data

http://support.apple.com/kb/HT4910

Cheers,

Jason H.