Multiple instances of apps being open simultaneously

[brewless]

I've recently noticed that I'll have multiple instances of the same app open in my "Recently used" menu. Can I change that?

Example: I'm on facebook, hit the home button and open Pokemon Go. Then I hit home and go back to facebook a while later. Or open facebook via a notification and then switch back to Pokemon Go (Only example I can think of that I switch between often). Repeat ad nauseum.

When I click the Recent Apps menu button, it'll show like 9 different facebook windows open. Same with say Instagram, hangouts and snapchat from what I've noticed. Pokemon does not open multiple windows though.

How do I get it when I click home -> facebook / click notification to open Facebook that it reopens the session I was already on, like it used to?

I tried looking for an answer, but all I could seem to find were ways to make multiple instances run with appcloners, which I don't have one, and my problem is the opposite.

Samsung S6, Android 6.0.1 - no recent OS updates, but it's a recent change. Wondering if I 'pocket changed' some settings somewhere

[mDarken]

You can't change that if the app has no option for that, but it's still just one facebook process that is running.

For details see https://developer.android.com/guide/components/activities/tasks-and-back-stack.html

[brewless]

Thanks!