Printing problem in Leopard

So you are saying that you are choosing one printer to print, such as a HP printer, but goes to like a Cannon printer or is like all the printers you have the same model and the computer cant tell which printer is which?

It sounds like your printers might be pooled, though I'm not sure how that could have happened by accident. I suppose it's possible that if one user set this up on one machine it might somehow be affecting the others on the network.

A printer pool creates one "printer" everyone can see, but when you print to that printer it selects whichever member printer is free and prints to that one. Unpredictable sometimes.

In System Preferences, in the Print & Fax pane, your printers should be listed down the left side. If there's something there that looks like three printers stacked up, and you click on it and in the main area it says "Kind: Printer Pool," try deleting it.