IOW, as I suggested earlier...If the first players ball is hit by the other ball into the hole (and was not observable from the tee area), the first player would have a technical Hole-in-one, even though it was moved by an "outside agency". To further complicate matters, if someone on the next tee saw what took place, but didn't tell the players in the group and the player who hit the hole-in-one (as he believed it to be) signs the scorecard, he would be disqualified for signing an incorrect scorecard.
The rules are an absolute mess.