The Universe doesn't operate on a scarcity-based principle, unlike most humans. :)

There is always enough of everything for everyone.

If both are in alignment with what they want and even if, by human standards, there appears to be only one object or situation, the Universe will still find a way for both of them to receive what they want.

Mental Power is creative power, it gives you the ability to create for yourself; it does not mean the ability to take something away from someone else. Nature never does things that way. Nature makes two blades of grass grow where one grew before, and Mind Power enables men to do the same thing.

The Master Key System

If you are talking about an artificially-manufactured situation like, say, a sporting contest between two people with only one prize then whoever has the lesser resistance will win. i.e. the one who best manages to balance their desire for winning with their belief that they can win. From my observations, this dominance can shift back and forth between the players over the course of a match.

But, even then, that doesn't mean that the loser won't receive the essence of what they were in alignment with outside of the artificially-manufactured match situation

For further thoughts on this subject, see here: Who wins if two people have conflicting desires?