Combining the results of multiple models and then adding another layer onto the combined output tends to increase accuracy / reduce error rates. (not new to AI: it's been done for over a decade)

But how to combine the results?

Usually just by concatenating the final hidden states (before any classifier/regression/image output head)

In this case, the first model generates a general image, and the second model handles finer details

Many ways, for one: https://magicfusion.github.io/