Why get two of the same receiver? Thats no fun, for the 5.1 in the second system check out Rotel, delicious amounts of power in a scrumptious looking box. Also check out Arcam, though their new models do 7.1 now
(Rotel decodes 7.1 but I believe the lesser cost model only powers 5 channels, the nicest rotel powers all of them; arcam powers all the channels it decodes.)

1xAxiom ax 1.2 2xPolk Audio R30 2xMordaunt-Short 3.0 H/K AVR 225 Paradigm PDR-10 Sub HTR MX-500