Connecting 2 transformers to each other isn't recommended. And could even be dangerous.
Using just one 32 va transformer wouldn't release the full power of the 6021. The maximum output of a 6021 is 2,5A, so 2,5A x 16V = 40 va. I would recommend using a simple 52va transformer (Viessmann 5200 or alike) but if you're running no more than 2 or 3 locos, one 32va transformer will do in most cases. (Depends on extra functions, like sound and other differences between locos)

Thanks for the information, I had a feeling it was a bad idea. Kent