me and my best friend, whose alias is ShadowJester, have had similer experiences.
Jester actually shows up a lot on these boards, such as Jester47 (who started this thread). The Jester, Bloodjester, DarkJester, and DeathJester.
To me, the most disturbing coincidence is GrimJester, a combination of me and my friend's names. Freaky.
And DeathJester is also freaky because my handle used to be The Grim Reapa, until I shortened it out of laziness, and, possibly, coolness.
I've actually had a lot of weird experiences with handles, especially with how I made them. Like my friend Jason mistyped his name, and instantly became Jaspn. Or my old alias was hobinkobad, my first DND character, and a name I came up with when looking through the MM and seeing Hobgoblin/Kobold. Freaky.