Errors off hitters cards??

This has probably been answered before but:
A 1-6 was originally rolled on Jeff Bagwell's card which resulted in a double (no field indicated). There was a man on first and second. Bagwell ended up scoring on the play with an error charged to the CF'er. I assume in real life this simulates the CF'er throwing the ball into the stands or something along that line, which I would not question if it resulted from an "X" chart reading.
My question is: by what gaming mechanism is this result triggered?
Is there some super duper advanced rules?
A 1-6 was originally rolled on Jeff Bagwell's card which resulted in a double (no field indicated). There was a man on first and second. Bagwell ended up scoring on the play with an error charged to the CF'er. I assume in real life this simulates the CF'er throwing the ball into the stands or something along that line, which I would not question if it resulted from an "X" chart reading.
My question is: by what gaming mechanism is this result triggered?
Is there some super duper advanced rules?