Why are two different streams of post shown between the Facebook and Metal Facebook Apps?

[Android Central Question]

Both apps running on my phone to lots of stories being shown at the same time?

 

[SpookDroid]

If both are using FB's algorithm and not showing posts chronologically, having two apps (or more than one session of FB open) is the reason. Basically, one app is telling FB which stories have been displayed and 'seen', so the other app shows a different stream because of those posts the algorithm 'thinks' have already been seen before.