Strange printing problem

[joe at actionline.com]

When I send a one-page document to my HP LaserJet 4 printer, it prints
one copy just fine.

But just recently, it has begun to print double for any documents for
which I request more than one copy.  If I ask for 2, it prints 4; if I
ask for 3, it prints 6.

It does this from both Libre office and PDF documents.

What could be causing this strange behavior? And how can I fix it?