If I'm dropping $300 for two it better be outstanding or I'm never coming back. A send back on two identical orders is hard to understand or excuse. Someone suggested OP should've switched steaks. A nice thought, I don't disagree, but at a minimum I would not have touched mine until the other one came back. Either way, the $300 meal is compromised.
I put it on the restaurant to try to make things right. Sure the customer can complain and probably get free drinks/desserts/whatever. But as soon as that steak got sent back they should've gone into damage control. The customer should not have had to complain any more.