words - Is 'A father and son sleeping with a betrothed young woman on yom kippur' an expression?

Bava metza 83b:

Rabbi Elazar brebbi Shimon is afraid that he may have wrongfully caused someone to be hanged, but is reassured that the hanged and his son 'slept with a betrothed maiden on yom kippur'

Gittin 57a:

A story from Kfar Sekania in Egypt: grain became slightly more expensive, they investigated and found that 'a father and his son slept with a betrothed woman on yom kippur' they stoned them and the price returned to normal.

I was wondering if any one has any insights in to this phrase. It jumped out at me, as it has occurred twice while I have been learning. Is it literal? A saying? Is it the same occurrence? Rav Minyomi bar Chilkiyah, Rav Chilkiyah bar Tuvia, and Rav Huna bar Chiya, who discuss this tale in Gittin, all seem like amoraim since they have the title Rav and not rebbi, so they could be relating the events that led to the people discovering that Rabbi Elazar brebbi Shimon's culprit was in fact guilty. (After being stoned people were hanged, see Devarim 21:23.)

There are peculiar terms like this in the gemarah, like a 'bone for choking a mother in law', (gittin, 67b), or 'white geese', (also gittin, 73a), but rashi explains those (ibid).

Any thoughts greatly appreciated!