Riddle: I'm useless when one but useless when two

It seems like there's a bit of a puzzle here! Let's break it down:

- "Useless when one": This implies that the item in question has no utility or purpose when it is alone.
- "Useless when two": This implies that the item also has no utility or purpose when there are two of them.

Without additional context, it’s challenging to pinpoint an exact answer, but one possible interpretation could be a pair of socks. A single sock is generally considered useless, and even two socks of different pairs don’t serve the intended purpose. For socks to be useful, they need to be in a matching pair.

However, if this interpretation doesn’t fit, please provide more context or hints!