Is it OK to apply a coat of one brand of paint over a coat of another brand?
On the face of it, that's not a bad idea.

I would only be worried about a few things, though:

One, is about the actual sheen that each brand presents. You really want to try both out on a scrap or hidden wall and make sure the brand you want to have show up on top is carefully selected.

Two, is about how easy will these varying coats be, for patch repairs as life happens.

Three, you generally don't double-coat your cut-ins. For example corners, around trimwork, etc., are mostly just a single coat (and you would roll as close to edges as possible), and doing two separate brands' coats on the entire wall surface will take a lot of (possibly thankless) work.