He probably means the last vertebral and sometimes supracaudal scutes. In some Aldabra tortoises, the last vertebral scute (and sometimes others) can be developmentally divided to varying degrees. The anal scute is on the plastron and is of no particular note in this context.
I do not see a question, though, so I do not see a place to shed any light on the matter, but I will add a bit of general stuff.
Split scutes often occur at higher incubation temperatures, but it can occur due to other reasons, too. I do not bank on it for early sexing like some do, as I have had plenty of animals with split scutes end up being male. They are harmless developmental abnormalities. Not typically genetic (although it could be a possibility in some limited instances), as it can arise without split lineage and split-scute animals give rise to plenty of developmentally typical (non-split) animals.
I do not typically like split scutes, as I dislike asymmetry, but I do not mind it so much if the splitting is mild or symmetric in conformation. My Aldabras have mild split scutes. One of my adult het Ivory Sulcata females has split scutes. The rest of my current animals have no such cosmetic imperfections at this time. Split scutes do not adversely impact health.
None of our adults have any split scutes, however we did hatch out one with a split scute. High incubation temps were not a factor and 11 others from the same clutch were normal. The new owner relates that the split is not growing in any way.