How does it work when you Soul Jump twice?

Something I have been curious about and since I don't really know anything about how MapleStory works I'd thought I ask.

Sometimes it seems to happen randomly, but there is one time it always happens and that is when coming through a portal and you hold down the key you place Soul Jump on.

Same happens to me. I remember there used to be a glitch where if you did that with any other skill, you would attack twice in one attack, so NL's
could throw 12 stars instead of 6. It was crazy. They fixed it, but it still happens with some skills

Same happens to me. I remember there used to be a glitch where if you did that with any other skill, you would attack twice in one attack, so NL's
could throw 12 stars instead of 6. It was crazy. They fixed it, but it still happens with some skills

[press skill] + [mount riding] + [press skill]