Mixdown Volume Aa 2,0

[sikter]

I was reading about this issue somewhere but I just can’t find it. Maybe it was not on this board.

Here it is:
I do mixdown in AA 2,0 and volume is pretty high and there are actually places where several peaks hit red at metering bar.

I wouldn’t bother and I go on. I save this mix on my PC.
Then I import it as audio file back to one available track in AA 2,0 and the highest peaks show -3 dB.

Why does it this happen? Should I use bounce mix?
Does AA 2,0 correct my HOT faults automaticly?
Should I do normalize it afterwords?