Aaron Cowan of Sage Dynamics discusses and shows a slight variation of off axis shooting. I usually see off axis shooting in 3Gun competitions where the shooter has an angled sight zeroed differently than his or her main sight. This way you can stay zoomed in for longer range targets and rapid transition to the angle sights for close range targets.

Aaron Cowan uses dual red dots on one of his rifles. But the second angled red dot is not for different distances but rather for better concealment and ease of use when shooting prone.

Traditional Prone shooting

Off axis prone shooting

The determining factor of off axis shooting is usually shooting underneath concealment, There is a problem that arises and that is the bullet trajectory of a canted rifle. For those not familiar with with off axis/canted shooting this may be helpful.

Here is a screen shot of the target from 100 yards. Circled in blue is from the traditional prone position. Circled in red is from the canted prone position.