There'd only be one meal. If you go back in time to eat your own meal, then your past self will have never eaten it. A second meal wouldn't appear out of nowhere, it'd need to come from some place.
I'd imagine for the sake of a stable time loop that making for the one robbed of a meal going back in time to eat the meal himself. In the end you're only eating the meal once regardless of how much effort you put into it.
What tc said.
Just like in Back to the Future. I'd collect lists of winning sports teams and lotteries and bring them back to right about now. I wouldn't want to be some past self with all that money. I'd probably get robbed blind. I'm good with who I am now, how I would use the cash and who I would cut out of my life if I could control the lottery numbers.
(Yeah. If I were to win the lottery right now, without the help of time travel, I'd still dump a few people.)