I was reading your question and thought to myself "probably some idiot thought it looked cute"... and then I noticed that it was Time::Limit, so that idiot was me!

Yeah, I probably thought it looked cute, or would stand out better, or something like that. It achieves nothing over a single negation.

In the case of overloaded objects, it actually could return something different from a single negation, but fork ain't likely to ever return an overloaded object.