My hp 1320 prints multiple copies instead of one copy

What document you are trying to print?
If it is Excel or Word document you have created a second blank page, reopen the document and delete the second empty page.

check your print preview. Either Excel is set to print multiple copies or the spreadsheet is slightly bigger than a page. Fix the spreadsheet, this is likely not a printer issue.

This *might* be due to a setting at the printer. You said it's a 1320tn and you're using a USB connection. Is the network part of the printer being used? (is the printer also connected to a network)

It is probably printing the other half of the spread sheet, although it is one page.

downlode the proper driver of 1320 for vista

set the number of copis in the printer to 1, refer to your user manual

The best thing to do as a starter is:

1. uninstall the print driver THEN
2. download the latest version from the manufacturer and install it

This rules out the driver as the cause of the problem
1. Go to printers
2. Right Click on the Printer HP Laserjet 1320
3. Click on Printing Preferences
4. Click on Advanced
5. Double Click (to open) on Paper Output
6. Ensure that COPY COUNT is set to "1"

If it is already set to one, trick the system a little:
1. set it to 2 and save that setting
2. then go back in and set it to 1

Good luck

This problem is caused by Mopier Mode being enabled by default. The idea of Mopier Mode is to minimise computer and network traffic by sending only 1 copy to a printer equiped with suitable internal memory. That stored copy is then used to produce the multiple copies. Most HP Laserjets do not have suitable internal memory and so only the one copy sent by the computer gets printed. To disable Mopier Mode:
Click Start
Click Devices and Printers
Right click your Laserjet Printer
Select Printer Properties
Click the Device Settings Tab
Scroll down to the bottom
If necessary, expand Installable Options
Click on Mopier Mode
Select Disable in the selection box that appears
Click Apply
You will now get multiple copies.

Windows may have eaten its baby again- that is, the driver for that printer.
Open the Control Panel, then Printers and Faxes, delete any listing for that model of printer, make sure the printer is on and connected, then reboot your system. This will force Win to 'find' the printer and install an uncorrupted driver for it.
(=Plug and Pray) 

If you cannot print more than 1 copy, click on...

Start -> Control Panel -> Printers -> Right click on HP 1320 printer icon -> Properties -> Device settings -> Disable mopier mode (last option)

This worked for an HP 1300, 1320 and as well as an HP P2015d using the HP 1320 driver.