iMac 2.66GHz 10.6.3 4GB RAM --
Mail.app determines an email is junk (does this well), then puts it in the Junk Folder (as it's supposed to) *and* puts a copy of it in the Trash folder. I don't have any Rules set up. Just the standard instructions in the Junk Mail part of the preferences.
Why the duplicating into the Trash folder? Any ideas why this is happening?