I made a Tee Shirt with a small Stormy on the front shoulder and a larger Stormy on the back, with a slightly different pose. It was an iron-on type, and I simply printed it using an inkjet printer.
Front
and
Back
Next time I'd wash the blank Tee shirt
first to make sure it is preshrunk. And I'd make the back picture bigger and the front picture closer to the midline.