One plausible explanation could be that the S6 Edge will have a higher base cost than the normal edition so Samsung decided it would be best to give people more for their money. We’ve seen that pricing model in the Samsung Galaxy Note 4 and Samsung Galaxy Note Edge so it wouldn’t be a shock to see it repeated here.
Of course, we could just be jumping way ahead of ourselves and this could all be a mistake. It’s also worth remembering that this could specifically be for the UK and we might not see the same structuring for other markets. We’ll do our darnedest to find out from Samsung themselves, though, and will update this post if we find out anything more.