This sounds similar to some other listed bugs of multiple notifications but I'm not sure if it is really the same bug: E.g. after finishing a copy job, I'm notified. I have three monitors and on every screen I have a control bar. Using three monitors, I get three notifications on every screen. Using two monitors, I get two notifications on every screen. May be a problem of multiple control bars or may be a problem of multiple screens.
Did you add a "default panel" to those screens? the System tray applet contains the Notification applet by default, that's why you get multiple notifications
yes, "defaul panel" or "Suse default panel" to see the status items at every panel. So then this is correct behavior? But all the messages appear at one panel, I think the one of the main screen, and not one message at each panel.
isn't shown multiple times at each screen any longer; only one message per panel!