This is an intermitent problem. I had it when CS5 was new. Now it has returned after 3 years. I get an unpredictable number of copies from my HP Officeje Pro 8000 Wireless printer when printing from Photoshop CS5. I do not have the same problem printing from other programs.
The problem is that I don't get the number of copies I ask for. If I set the number at 4 I may get only one. Some time later if I ask for 1 I may get 4 or 3 or 2. HP support asked me to "clear the print cache" by stopping and restarting the print spooler in the "services" list. That rectified the problem when it first happened, but now it has returned and the same process seems not to be helping.
There has been a problem reported here on the forum in which under some conditions the settings you select seem to go into limbo for one iteration, before actually being applied. Thus, what you may be perceiving as random copy count changes may just be the copy count you tried to select last time.
Try this to see if it makes your copy count deterministic:
1. Change your copy count.
2. Press the [Print Settings...] button.
3. OK out.
4. Press the [Print Settings...] button again.
5. OK out again.
6. Now print and see if the copy count is as you expect.
The double [Print Settings...] operation seems to push the change all the way through to the printer driver.
Thanks, I haven't yet experimented with you suggestion, but from you description this is what is happening to me. The number of copies is not random, but the number I previously set. Seems a strange quirk, but nice to know about it so I can head it off. By the way, I like your word "deterministic."