Hi Aquila, thank you for your reply
You are correct, you could unwrap different parts of your model in one UV map, and let them overlap, like shown in the pics you included. But, for convienence (well i thought it was convenient) i created a different UV layer for each material. Take for example a bottle of wine, where you have a cork texture, a bottle texture and a label texture: you have 3 materials, 3 textures and 3 UV maps. Now i want to bake everything into one consolidated texture/uvmap (blender 2.49 used to have a consolidate script which did that automatically but it can still be done 'by hand'), this produces a 4th consolidated UVmap and that is the one i want to include in my collada export, but that doesnt seem to happen when i set that one as the "active rendering layer" in my UV map list.
I hope i am making sense here :-)