How does one bake a repeated UV texture?

I’ve got a parquet floor that uses a slatted wood texture. So far so good. Now I want to bake shadows onto that floor, but when I do, the faces, which previously each had their own copy of the wood texture, try to all share one large common copy of that wood texture across the entire unwrapped mesh. Is there some two-step process whereby the original UV textures can remain as part of the source model while a new unwrapped texture is being baked?