UV unwrap (map) faces to multiple images?

My object has one material and this material has one texture - a jpg image. I also correctly UV mapped all faces to this image.

The problem starts when applying a second texture (also jpg image) to the same material. I can’t find out how the new mappings should be done. The images are not the same size, so the mapping of faces should be completely different. When I load the second image and make the “unwrap”, all is messed up with the first image…

Is it possible to have 2 different mappings of a group of faces, each attached to a different image? Or is it possible to have only 1 mapping for a group of faces per object/material? In the second case, how to apply multiple images as textures? (maybe use Gimp to apply the second image to first with correct proportions and then use this final image - it should fit into the existing mapping).

You can have multiple UV mappings for the same object, then use the different UVs for different textures
Blender 2.49

Blender 2.5