Silly teachers and schools with their silly no-good-reason limitations.
Not allowing a 2nd uv is just plain bonkers.
Oh well, you dont need to unwrap both the wood and stone on the full 0-1 space, you could give each half and just stretch the texture with a texture coordinate node.
You could also make a mask, use vertex color, or many other tricks.
Heck, could forego UV0 entirely with world aligned mapping (more expensive), and more complex ways.
But, yea you can have them overlap and use a mask or whatever to show only one material.
two id’s/materials results in the mesh being drawn/called twice, (drawcalls) so its better to use one material.