Merging duplicate contact entries from multiple sources I have multiple copies of the same contacts on my phone, from the Google account associated, and phone contacts etc.

Eg., for a single contact I might have:


2 copies on the phone 
1 copy on my Google account (synced)
another copy in some other location


This happened on my HTC Wildfire a year ago and now I'm using a Samsung Galaxy S2.

Is there a way I can merge all related contacts and delete the other extra copies? It'd be helpful if I could do this from my PC.
Remember: when creating a contact, you can decide where to store it. Usually, there are at least 3 choices: Google, SIM, phone.

If I read your question correctly, it looks like you have a copy in each of these places. In this case, Tirath's suggestion doesn't work, as GMail will only see what's sync'd there (and phone + SIM don't get sync'd). You then might want to take a look at apps like Contact Remover (to ease deletion of the duplicates), or Contact Remover Plus which also offers to merge or move them.