Is it normal for a MacBook Pro battery to regenerate itself? Let me first give a quick background. I got the 2015 MBP 15" with Retina display second hand like a week ago. As every normal person who just switched from Windows to Mac I was doing this and that and testing the battery life. No external software was used for the battery tests, only normal usage. I also got few battery tools which show more detailed information about the current state. 

Here it comes the question. My battery's max capacity seems to be..regenerating itself..

2 days ago this information was taken from one of the tools:


And here it comes the surprise. Today I took another look and had this shot taken:


As you can see the second picture shows that the Current max is higher, which I believe is strange ? Shouldn't it be going the other way - being lower with every cycle ?

The tools I've used show the same information, so it is not an issue there. They are Battery Health and CoconutBattery.
There are a lot of possible explanations.  The indicator that reads battery status isn't a perfect measure.  I've seen that kind of behavior on mobile phones (uneven discharge followed by a "full charge" don't necessarily give a perfect indication of actual battery capacity).  Given that the difference you observed is around 150 mAh (out of 8755?), the difference is pretty low (less than 2%), I'd expect that to be within a margin of error for the tool.

It's also possible that the tool you're using to check capacity might be measuring total capacity by the time it took to charge the battery from a "low" state to the current state, and extrapolated max capacity from there.  That's an indirect measurement, and could be off by as much as a percent or two.

You're right, though, a LiPo battery doesn't really "improve" with age.