Baking normal map from one UV to another

[stray]

@JRRRRRR

does it like a albedo texture and seems to ignore tangents

I vaguely remember having this problem, but not in every case (?), which made things very confusing.

Eventual “solution” went like this:

@stray

Normal values didn’t bake correctly (something to do with tangent space and UV maps?), there were seams and other indescribable weirdness:

I’m pretty sure there is some way to fix it, but nothing comes to mind now.
Came up with immediate random solution: bake to original UV map in Object space, then bake again in Tangent Space Well, it worked, so I’m not complaining. But I can’t say I understand this process either