A split twist is an ear twist that is split/twisted in half again, this is a good twist to use when doing the pop twist.
As if you just use an ear twist either side of a pop twist there is a very high percentage chance of it deflating.
If you want to have two ear/pinch twists together, by making them this way the bubbles will be a lot firmer & tighter together.

From some lecture notes that I made a few years back, this is another way of making the two ear/pinch twists although this way the ear/pinch twists would be slightly larger than above but which is exactly the same as a split twist