Sometimes we do double ups, why who knows but we do. This is how you can merge them into one.
Go to Contacts > Groups
Find Smart Groups where you will see Possible Duplicates
Click on Possible duplicates and then find the duplicate you wish to merge this time.
You will see in the top right hand corner the words Merge All 2 contacts. If they are more duplicates in there it will read Merge All 3 or 4 etc. contacts.
Click on Merge All (2) contacts and this box will appear.
Click on Merge and your contacts will now be combined into one contact.