I believe there is a bug in WordPress that for some reason has the affect of not always showing the correct menu function specified (when the script defined it). This happens with all plugins I have except the ImageHeadlines plugin which uses a very eloquent method of plugin option display.
To replicate this bug, find two plugins that adds a submenu each to a top-level menu. The right-most menu option displayed will overwrite the one(s) to the left of it.
I know of no fix or hack for this at the moment.