It sure is. What you'll need is the userid of the user that is going to remain. Once you have that, you'll go into the control panel and edit the user that is going to be merged. Down at the bottom there are a few tabs, one labeled "Merge User". Click that and you'll get a prompt for the userid that I referenced above.
On the next screen you'll get a comfirmation of what will actually happen so you can be sure you have the proper users to be merged.
