Yes, I've gotten The Sandgoose from it. I believe that chest is just like the one in the Sanctuary's trophy room, but I'm not 100% sure. Anyway, the chest in the trophy room will give you one of the better legendary weapons (Dragonstomper, Swinging Sword, Chickenbane, Sandgoose, etc.), but you will always get the same weapon from that chest on a certain gamertag no matter how many new Heroes you create. For example, each new character I create on my gamertag will always get the Dragonstomper .48 from that chest, but it might be a different weapon for someone else. Like I said, I think the 50 silver key chest at Bowerstone Castle is like that too, but I'm not 100% sure.