Well I still can't figure it - Paddy's example seems to have a flatter forehead than the two Museum Victoria examples. One of the Museum Victoria examples seems to have a less defined eyebrow, as does Paddy's. Paddy's has a uniformly thick rim but the two Museum Victoria examples have rims that are much thinner on one side.
The arrow in David Groom's book isn't clear either - it looks like it's pointing at a nick in the eyebrow.
I'm tempted to say they're the same design and that difference is due to strike pressure or using an old proof die or something, but without a definitive image of obverse 2 it's up in the air.