Possible Duplicate:
Remove Duplicate Second Unity Launcher on Dual Screen
Kind of hilarious, given this recent question, in which somebody asked if they could have the launcher on both screens, and the answer is "12.04 might help with that."
I installed 12.04, and now the launcher appears -- uninvited and unwanted -- on both of my screens. I was perfectly happy with the launcher on the left of the leftmost screens!
Newbie, so I've tried tinkering with my X settings, to no avail. Any advice?