Well, I can provide an update now after some further discussion with the Guest Service Executive Department.
As suspected, it’s no dice when it comes to obtaining credits for both stays. To be fair to Accor, they’re making it clear that their “…system is designed to prevent multiple stay credits for the same time frame and that [it’s a] standard practice across their loyalty program to ensure fair and consistent treatment for all members.”
I requested clarification around how they determine which stay is to be credited when overlapping stays are detected. The response was -:
“Our system automatically credits stays based on the first hotel that successfully posts a valid stay into the Accor ALL loyalty program system. When multiple stays occur simultaneously, the system will accept the first validated stay and automatically reject subsequent overlapping stay credits.”
In my specific example, the stay that was not credited would have earnt me more points than the stay that posted. I asked whether they could manually override this and credit the more lucrative stay, which they’ve agreed to do. Ultimately not the outcome I was hoping for (as suspected and posited to be the likely case by others in this thread), but certainly a better outcome than had I not enquired at all.
FWIW, my query was clearly escalated to a more senior team and they have been most informative and helpful in explaining the specifics and clarifying the whole situation.