Scenario 2: Same as 1, wake up in new body, etc. But they also wake up the old body. "Hey, I thought I was going to be in a new body!" They point at the young "you" doing a happy dance. "We just wanted to show you that it worked. Congratulations. Now lie back so we can deactivate you." The other one stops his happy dance: "Let's forget about that update ten years from now."
That happens every night I go to sleep and a fair portion of my atoms get swapped out by normal metabolic processes. My neural network changes as I'm unconscious or dream. I don't even remember all my dreams, but wake up with new thoughts/ideas sometimes.
We're always some delta from ourselves the previous day. I'm very different from the me of 10 years ago. The jump to a brain simulation may be a large change, but I could also tweak the things that didn't feel quite right or match with what I used to be like.
Resource constraints are certainly an issue; the fairest way seems like pre-allocating a subset of resources to each duplicate who in turn can do the same. Societal restrictions on creating a duplicate with too few resources would prevent effective slavery or abject poverty.