Here is the full list of all 8 Duel VR achievements.
You shot the mysterious man.
The mysterious man escaped.
Get the potato reward in all the arenas.
Get the dollar reward in all the arenas.
Get the gold reward in all the arenas.
Get the diamond reward in all the arenas.
Get all the cans in the range to fall into their pen.
Shoot the hat of each hatted opponent.