Vista 20P + AD12612 - One transformer or two?

I am adding keypads to my Vista 20P (Tuxedos). So I got the AD12612 and ordered the 1361X transformer for it. I have read mixed results on whether I should use 2 transformers, the 1321 to power the pannel and 1361 to power the AD12612, or just use the 1361 to power both.

Any advice on this would be appreciated. Thanks!