In the main settings cogwheel, click on Contacts in the lower section of the menu.

In the main contact list, find the two contacts that you're looking to merge. As you find them, click on the checkbox to the left of the contact ID to select them to be added to the merge function.

Once you have all of the contacts selected that you'd like to work with, click on the orange "Merge" button in the upper right corner.

If there is no conflicting/differing information between the contacts selected, there will only be a Save button visible.

If there is differences in the information for the contacts listed, you'll want to select the piece of information that you'll want to keep. This can include punctuation differences, as well.

Once you have all of the desired information selected, click save.