I checked my copy of the writers' technical manual that I was sent when I was invited to pitch for the show way back when, and on its plot of the bridge, that console is labeled simply "Tactical." The description is: "Responsible for weaponry, defense, and internal security, this is a small dedicated console directly behind the command area. In crisis situations, this console can be occupied by Tuvok or another tactical officer."
It doesn't explain why there's a second Tactical station along with the main Security/Tactical station where Tuvok was normally located. Maybe it was just in case they needed to set up shots where Tuvok was in the same frame with Janeway and Chakotay, or to provide directors with variety. Or if they needed someplace where an extra could stand and have a console blow up in their face.