racket99, I got the same confusion at the beginning. But they are sepparate functionalities. In fact, seeds fixed the division of your data set, and you training and validation will be always the same. However, data.show_batch is just a visualization tool which shows you random sample from your trainning set. i.e. if your trainning set has 1000 samples, show_batch will show you 12 - 9 random sample from those 1000, but those 1000 in your trainning set are always the same. If you want to change your 1000 images, you should change the number inside the seed.
Hope this was clear