Question about Recording

[Mc Cubz]

dont knw if this is the right section sorry. anyway..

are most rap songs recorded twice all the way through exactly the same and then mixed together?

if so:
do you play one through each speaker (left and right)?
how do you add reverb to a multilayerd vocal recording,
i.e. do you add the seperate reverb to each of the 2 layers individually or just to the
whole vocal layer of the song?

any help is much appreciated!