Ghost document keeps printing

Maybe the printer is possessed. Have you tried purging the print queue on the actual printer?

I'm not sure how to do that on the printer.  I did check the Spool directories on the PCs and there were no documents.  Yesterday, on the Macs, I took the following steps:

A.  Clear Print Queue on Macs:
     1.Launch Terminal
     2.Type cancel -a -

B. Uninstall and reinstall HPLaserJet printer (on Macs)

So far, so good.

No luck.  It's strange.  The first page of the Doc1 always prints three times.  Just printed again.

Most printers do not have a built-in queue, they use the spooler on the PC/Mac.

Periodically/randomly a document that doesn't exist

Your last comment said "the first page of Doc1 always prints 3 times". Does that mean it is now no longer random? In that case I'd say there is something funny about the driver you just installed.

No.  It's random.  It can print anytime during the day and sometimes goes for several days w/o printing at all.  The printer was deployed to the PC computers using Group Policy.  I've now unlinked the GPO from the OU the computers are in and will connect them directly using the IP address.  I'm going to see if I can do a factory reset on the printer.

I doubt that the factory reset will fix this (but by all means try it). Printers do not keep documents in memory, it's the queue on the PC/Mac that does that. A direct IP connection is more likely to fix it. If it does, at least you'll know where to look for the real fix: the server.

And I'm still confused, as your question also states that what prints is "a random document that does not exist". Could that imply it's a document from outside your organisation? But then, you also said that "the first page of Doc1 prints 3 times".

I've deleted the printer off the Windows print server and all the computers now have a direct IP connection to the printer yet the document still printed (out of the blue) yesterday.

I misspoke when I said it was a random document.  It's the same document inside our organization that doesn't seem to exist on our file server or on anyone's workstation.  The first page of this document randomly prints three times -- always the same document, always three times, always the first page.  The last thing I'm going to try is asking a person using a MacBook if we can switch computers with her, that is, reinstall the OS on her Mac while giving her a loaner Mac.  If that doesn't work, I'll swap in a new printer.  But I'm outta ideas.