If you have three, you have three. If you have two, you have two. If you have one, you have none. What is it?
This is kind of a play on words, but:
If you have 3 options, you have 3 options. If you have 2 options you have 2 options. If you have only 1 option, you don't have any options.
Along similar lines, this works too:
If you have 3 choices, you have 3 choices. If you have 2 choices you have 2 choices. If you have only 1 choice, you don't have a choice.
Is it a
If you have triplets, you have three multiples. If you have twins, you have two multiples. But if you have a single child, you have no multiples.
Original answer, not correct by the precise definition (thanks @Will):
If you have three organisms with the same DNA, you have three clones. But if you have one organism it is not a clone.
It may be about physical sharing, and telling other people what you have.
If you have more than one unit of something you can inform your surroundings on this and share it with them.
On the other hand: if you have only one, telling others might induce envy and you may be better off not mentioning it.