I think it boils down to that little word "unique". Just because Phil's experience is unusual doesn't mean it's unique.

Phil mistook ducks for a UFO.
X mistook ducks for a UFO.
Therefore X is Phil.

This is true only if the experience of mistaking ducks for a UFO is strictly unique. However, the evidence of Phil's book demonstrates that this is a false assumption, since he was with other people at the time (who presumably shared his misperception). So X could be one of Phil's companions that day, just as easily as Phil.

And let's not get too fussy here... I realize that (for a while at least) Phil's ducks were a UFO, not just mistaken for one... [img]/phpBB/images/smiles/icon_lol.gif[/img]