Printing Notification to wrong user

I’ve got two NT 4.0 users who are getting print notifications when the other person prints. I’m looking for help to find out where to look to solve the problem. One is on an IBM ThinkPad 390 with NT4.0 and service pack 4, the other is working on a Compaq Professional Workstation AP200 with NT4.0 and SP4.
Thanks.