If you don't have a manual, you can find one here
My guess is either on the printer or the driver. Skimming the manual, it doesn't seem that you can set the default number of pages printed per sent print job on the printer, but that is something I would look into. This is a nice office printer, perhaps the printer is set to print multiple copies of everything it is sent. You could determine if it is the printer or driver/computer by printing to it from another computer.
If it is the computer, go into the control panel and select the properties for this printer. In there, check if the number of copies is improperly set to 5. This would happen for every print job sent from this system.
Does it print 5 copies of documents sent from different programs (i.e. Web Page, Word, Excel)? Quite possibly, one time you set it to print 5 copies and that application retained that as default. In that application, rather than clicking "print" click "printer setup" and look through the settings to see if it is requesting multiple copies.
I am 95% sure one of these three solutions will solve your problem.