I personally have never seen 2 sectors after a red eye - I did not know that was happening!
I know for a fact that it has happened. the duty was DRW-SYD-BNE. An 11.5 hour red-eye duty, arriving home into BNE at about 1300. The last sector was a deadhead and "yes" it was perfectly legal.
Maybe if we didn't have to clean/cater on turn arounds we may be less tired.
I didn't think about that one. Imagine how much having to employ full time cleaners and giving the caterers more duties would cost the company.