I updated Photoshop CC last week, and now have Photoshop CC and Photoshop CC 2014 in my applications folder. When I open a file created in Photoshop, it opens Photoshop. However, if I open another Photoshop file (by double-clicking on it), it opens up in a second Photoshop app (instead of the Photoshop app that's already open)... so I have two Photoshops open at the same time. And both are CC versions.
You must be on a Mac will not happen on windows. Are you sure both open Photoshop versions is CC 14.2.1. Have you used menu Help>About Photoshop from both Photoshop windows?
Yeah same story here. Same versions and everything. Really odd.