Transfer UVs, meshes with same topology but different vertex ID numbers

[Anonymous]

I need to keep vertex ID numbers of my original mesh (since I used morph targets with it), I made the unwrap separately, I made a copy of the original mesh, deleted half of it, unwrapped it and symmetry it again, which cause half of the copied object to have different vertex ID numbers to those of the original mesh, "breaking" the UVs when I transferred the unwrapUVW modifier to that original mesh.

Any idea on how to fix it?

(I transferred the unwrapUVW from the copy to the original)