Likewise, better to have too much rather than too little stock! Half bottles are always a mystery, usually they're so close in price to a full bottle it isn't even worth considering the half bottle, but in this odd case it's cheaper for the half bottle, as I usually find to be the case with Canard Duchene.
I'd much prefer to buy two half bottles over a full bottle and be able to open a new bottle on two occasions rather that use a fizz saver. No reason that can't be on the same day either
I've also found the rosé to be a good drop, for reference my taste preference is on the Veuve/Louis Roederer side of the fence rather than Pol Roger/Bollinger.
Edit - my mistake, the flybuys offer is on selected products which doesn't include Canard Duchene so that adds $5 to the price.