Would you like to populate your own planet?

There is a religion (I won't mention any names) whose male followers (well it's a cult really) believe that they have to marry as many women as possible so they can have huge amounts of children sao they can populate their own planet. If they are good (and give loads of money to the cult leader) throughout their time on this earth then they will be granted a planet and they will be responsible for populating it.
Is this true...did I dream it...I could have sworn I saw a documentary about it.