Add a black clip to the time line.
Add a text filter with a frame counter.
Split the clip at the middle.
Pull the first edge of the latter clip to the left to create a dissolve.
Place the playhead over the dissolve. Two different frames numbers are visible at the same time(mixed), but only one should be visible. Or in other words the dissolve should be invisible, because the framenumbers should be the same.
Having a closer look it is the outframe of the dissolve which is doubled. Ex. if I make a split cut at 01:00 and drag to the left to make a dissolve, then the frame: 01:00 is shown twice - at the last frame of the transition - and at the first frame of the following clip.
This may be considered a minor thing, but if you use split cuts in the audiotrack to give different parts of a clip different volumes and then want to fade between the jumping volumes you’re in trouble with the double frame.