GPU choice

[Guoyfbb]

I have two GPUs in my computer, and when one of my GPUs is running the other program, I want to run Nekrs, but the program reports an error. I would like to ask how to choose the GPU model before running the program to avoid the above problem.I apologize for not being very accurate in my expression. Where should I add such a sentence to choose a GPU? And when my simulated GPU memory occupies more than 1 of the GPU memory, can I do GPU parallelism, and if so, in which part of the program can it be reflected?