The reason that lavender albino and albino don't breed to make an albino is because the two genes are in different gene pairs. It takes over twenty thousand gene pairs to make a normal ball python. A mistake in one gene pair produces an albino ball python, and a mistake in a different gene pair produces a lavender albino ball python.
It would be possible to get a snake that has two lavender albino genes in one gene pair and two albino genes in the other gene pair. One way to do it is to mate a lavender albino ball python to an albino, then mate their babies together. Every second generation albino has one chance in four of being an albino lavender albino.
I think that the effect of the two albino genes would mask the effect of the two lavender albino genes. The baby albinos would have to be raised to adulthood and given a breeding test to be able to tell the difference between an albino, an albino het lavender albino, and an albino lavender albino. So there is little reason for anyone to try to breed such a snake.
Hope that helps.