My friend showed me her $2 bill with a red seal and asked me what the red seal meant. (I don't know.) It's a 1953 C. The letter "F" appears twice on the front. I notice that the "legal tender" statement is a little different than I see on other bills. It reads: "This note is legal tender at its face value for all debts public and private." Can you tell me the significance of a red seal? Thank you.