[NETvoyne]

I agree he should have been disqualified for failing to correct the error of playing with the wrong ball.

According the the definitions in the Rules of Golf a ball is considered 'lost' if the player can't find it or can't identify it within five minutes. So, after realizing he had played a stroke with a ball he could not identify as his, I think he should have declared the original ball lost and continued with the provisional ball with a total of three penalty strokes (one stroke for the original stroke-and-distance penalty, and two penalty strokes either for playing a wrong ball or for playing a "practice" stroke.)