It’s like this – you’ve had this HP Laserjet 4M plus (insert your model here) networked for years and you’ve been printing with no problems in all that time until you buy a Mac. Now suddenly there are two copies of everything being spewed out and mountains of wasted paper.
Don’t go looking through the printer menus on the Mac it isn’t there. Go to your printer, take it off line. Hit the menu button until it says Printing Menu. Hit Item until it says Copies=2. Hit shift and +/- button until it says Copies=1 then hit enter. Put it back on line and if you don’t have an uncle called Bob then you should!