DOITQ: The coincidence is in the timing
Re >>2931038 (pb)
Twitter "media" filenames encode a monotonically increasing number using a 64 character alphabet. They are not a cryptographic hash.
https://twitter.com/realDonaldTrump/status/928325667556548608
https://pbs.twimg.com/media/DOITQJ8UIAAowsQ.jpg
https://twitter.com/realDonaldTrump/status/928286153672970240
https://pbs.twimg.com/media/DOHvQZkX0AEjfL9.jpg
'H' < 'I' ="DOHvQ" < "DOITQ"
Recent filenames start with "DmS" ('O' < 'm' in ASCII).
The coincidence is that POTUS tweeted in the timeframe where Twitter image names started with "DOITQ". A number of images posted on Twitter around the same time also start by the same letters.
So to estimate the (im)probability, we need to know the duration of the "DOITQ" timeframe. Is it seconds, minutes, hours, or days?