How do I use 2 gpus to train the same yolov3 model?

I'm having trouble training my yolov3 in my PC, which has 2 gpus of 8 GB. The problem is I can only train it setting Batch = 64 and Subdivisions=64. Any other value for subdivisions (32, 16, 8) generates an error: CUDA out of memory. The problem is I have 2 gpus and the program doesn't recognize the excess and allocate to the other gpu even setting flags -gpus 0,1 and compiling with CUDA. I want to lower subdivision to get a bigger accuracy. How do I use both gpus to train the same yolov3 model?