Maybe I'm missing something but I don't see how you can discern a coincidence from only one event. Only Pfizer/BioNTech have announced anything recently, no-one else.
It has been reported that Moderna may also announce some promising interim findings soon but as yet they haven't done so.
Where do you see a coincidence?
Even if it does turn out that two companies make announcements of interim results fairly close to reach other (announcements based, once again, on analyses from independent DMC's that the companies don't control) then is it really all that surprising when there are over 200 different candidate vaccines being worked on and everyone started at pretty much the same time?
Anyway, I feel I'm rather banging my head against a brick wall here so I'll now refrain from further comment on this specific issue.