Normally we provide UVs and Normals for each vertex. Is there a way to have them per polygon?

For instance, if I want to make a back face for a triangle I can simply use the same vertices however what if I want different UVs on the backface? Is there a way to achieve this apart from having duplicate vertices?

Normally I would have 6 vertices, 6 indices and 6 uvs (per vertex) but I’m wondering if there’s a way to achieve it by having 3 vertices, 6 indices and 6 uvs (per indice) so that there’ll be less vertices.