Tamas,

This is really the place to get the answer you are looking for.

The other forum is related to room construction.

Rod

Nothing special happens. This is standard procedure in most studios. You're then able to have more control over the sound of the snare by raising or lowering the levels of the bottom or top mic and EQing etc etc.

Most of the time you'll have to flip the phase of the bottom, but check it both ways to see which sounds better.

you cna move the bottom mic up and down until you get the sound you're looking for sometimes the drum will sound too thin so you will want to roll offsome high end form the bottom mic