Yes, if mean spreading computation between the GPUs, and not just rendering. Start a parallel pool with 2 workers
The default behaviour when the pool opens is for each worker to select a different GPU.
Depending on what you are doing and the dependencies that you have between one iteration and the next, you may find that parfeval or parfor is appropriate. If you just want to run the same code on two workers then you could use spmd. But in that case you might find it is easier just to start two MATLAB sessions and use gpuDevice to select different GPUs on each one.
Looking at your post I'm not sure any of this is useful to you because you are running plot commands, and they cannot use the GPU (except to actually draw the graphics).