These are great finds. The 2 pesos from the very first paper, the 1E1, is an uncommon stamp. On cover, it is even more desirable.
The first cover has a marking that has been crossed out. I looked it up, and it's a postage due marking. I am reasoning that it got crossed out after someone realized that there was plenty of postage paid on this cover. Maybe the person who applied it was used to seeing one peso stamps and thought the 2 pesos stamp was a 2 centavos stamp?