Hmm, I have not seen that happen in any version of PSP. Normally when you want to open the same image it just overrides the request and just opens it once..
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Otherwise you could try starting X with the Shift key down and reset the settings to default.
I don't use X, but I am sure it works the same as in the later versions:
If you have a customized workspace, save it first.
Close PSP. Open it again and hold the Shift key until you get a message that PSP is resetting to it's default state. Then release the Shift key :-)
Load the saved workspace.
See if the problem is still there.
Good luck :-)

Grenou