Can RVN coup happen 2 years in a row?
Also - on a card like Cambodian Excursion - if you don't activate the 0 RP event - does the card get removed from the game?
Yes, a coup can happen in successive years. I don't like your chances of winning tough.
Cambodian Incursion and a couple other "campaign-like" 1969 cards are not campaign cards, so do not remove them from the game if you do not do the event. I think they are removed in 1973 though.