Why i use multi_gpu to train my model the generated image became deteriorated

it is the another form of cyclegan,named augment cyclegan, the size of image in this code is 6464 and transform it to numpy data, where i want to change the size to 128128, one gpu is not work,so i use 2 gpus,i show the GPU state in wanch -n 1 nvidia-smi, and there were 2 gpus working, but the generated image is much deteriorated than use one gpu(the image size is 64*64 ) ,here are the generated image,one is use one gpu,the other is use 2 gpus.12 11