dual uvmap in blender for puddles

[giopanda]

hey guys!
i'm working on a supermoto track and i'm stuck at generating puddles for wet asphalt..

i know it's not strictly a mxb topic but maybe someone can help.

basically all i found are super old tutorials on the krp forums (totally useless since images hosted are gone, and so are youtube links) that explain that we need to export the track surface with 2 uvmaps, one for the texture and one for the puddles layer.

so my question is, does anybody knows how to export a mesh with 2 uvmaps from blender and make them work in game?
because in blender everything is correct, but it doesn't work in mapview and in game..

thanks!