Bob Dorr troubleshoots an issue:
When 2 or more workers are modifying the same row, it is possible to encounter 13535. The time of the begin transaction and the modification are the defining properties. When the transaction begin time is before the latest row modification, error 13535 is encountered.
Click through for an example of how you might trigger this error. This ultimately is the optimistic concurrency problem: how do you deal with multiple writers when using snapshot-based optimistic concurrency? Silently clobber or raise an error? Looks like temporal tables, like memory-optimized tables, raise an error instead of going quietly into the night.