communicate with two keithley via two gpib cables using python

Hi, I have a question about communicating with keithley. I have two python codes to control two keithley via two gpib cables. they work well when they run along, but when I run them together in single computer, one program stuck with problem like timeout. They have different port name. If you have any suggestion, please let me know. Thanks!

You have two keithleys and two gpib cables.
But how many GPIB interface boards does the computer have?
If only one gpib card in the PC, then only one program can take charge of it at a time.
A single program that sends commands to two different gpib address would be needed for simultaneous use of both keithleys.