Yep, that's just UOAssist in the back. Windows automatically tiles them together in the taskbar when I have too many other windows open.
I do sometimes run two clients though, but only with 2 Windows User Accounts and the fast-user switching ability. One account runs one uo account, the other account runs the other uo account.
It is perfectly legal to run 2 accounts at the same time this way as it is part of Windows and just the same as having 2 computers.
C'mon guys & gals! Lets see those UO Screenshots of how you have your game window set up! If you need me to host/reduce the file size of your image for you, just sent it to
[email protected] - I'll email it back to you or email you back with the link to the image if you need it hosted in my photobucket.