Undo and history in PS Latest version

On windows 10, PS cc, latest release. 

I recently noticed, I don't recall this hjappening to me before, but maybe it is standard, 

When working and paint some in PS cc. I then undo several steps and start painting again. My expectation is that the steps that I undo should be lost/overwritten  with the new steps but it is not the case. The undo works but the history starts adding after the steps I did undo.  So here is my testcase: 

1. Create a new file > New layer > paint several times

2. Check history and I see 

-New Layer

-Brush tool (1)

.. (19 more times) 

-Brush tool (20)

3. Undo , lets say 10 steps. History shows the the brush tool in step 10 highlihted. 

4. Paint again. 

5. History shows the same steps as before including the Brush tool (20)  pluse the new step added as Brush tool (21). So the histor jumps back to brush tool (20)  and adds a new step after it. 

My problem with that is if I undo again (a 2nd itme)  a few times it goes through hte setsp I did already undo and this is a pain. 

Any ideas ?