Players who don't respect the Private in Private Message.

On that note, if I send a player a PM, and then another player responds from their account, what the heck am I supposed to think of that? I think that's shady! Like, you're one person, don't play me with two accounts, and if you're two people in a room together, stick to your own freaking accounts! I don't want to have to talk to you through another player! What is this, the  third grade? If I'm your GM, and I send you a message, I expect you to reply to it, not your buddy Timmy or Randy or Lucy!