Generally speaking there are two problems with regeneration lithops can have. First is being too slow. Second is being too quick and doing to two times in a year. The second one isn't very problematic though as long as the leaf changes go safely. But you can forget about flowers.
I read somewhere that in case of lithops new bodies and flower buds are very similar in the early stages of development. Might the second regeneration be flower buds that have been "re-directed" at the early stage?
Btw, this schwantesii's pot-mate is doing it, too. Just like a bunch of my fulvis last year.