When you click the button to print, did it not start right away and you click the button a few more times?
Reason i ask is that depending on the size of the file your printing it takes some time for it to transfer the info to the printer before it starts to print, thus meaning evey time you click the print button it is storing that you want another copy.
I did this once, thought my printer wasn't working and must have clicked print 100 times and when it finally started to print it wouldnt stop, lol.
To stop it look in your toolbar for the printer icon and right click it, you should find a option to "open printer folder" or something like that, open it up and it will show everything waiting to be printed and you can cancel there.
If that doesn't work sometimes a reboot will clear the memory of it.
Also I find that my HP is the hardest to get it to stop printing out of all the printers I have owned

Not to mention the bloated software that they make you think is required to run the printer when all you need is the drivers installed off the cd
