My brother was sent two phones only charged for 1.

[Gulanowski]

It should be sent back. As Plato believed, you should not do what you know to be wrong even if you yourself have been wronged. So, even if you're pissed at Sprint because their TP2 is $200 more than Verizons or whatever Sprint customers are complaining about this week, you should still not seek retribution by keeping something that is not free, is not yours and should be given back to it's owners.