When I use the S key to split a video event, the frame which I am sitting on seems to wind up in both new events - at the end of the first and the beginning of the second. Am I misperceiving this?

I thought that the previewed frame would either a) go to the event on the left of the split point, or b) go to the event on the right of the split point. However, I do not seem to be able to get consistent behavior here. User error?

I would very much appreciate some guidance on this - thanks!