Better amp choice for 2 12 4ohm subs?

Alright i have 2 12's alpine type r's and they are dual voice coils. and are 4 ohm. i cant decide between 2 alpine mrp m500's or 1 mrp m1000. im looking for 500rms to each sub.. would i be able to use them on the m1000?? some say no because mine are 4ohm but idk or 2 m500's and are they over rated or underrated?? is it true 500watts?? thanks please reply quick. im just really needing help because i dont understand none of this ohm stuff. so would a m1000 work or not?? or do i have to get 2 m500's but would it be true 500rms to each sub with the m500s??