So my dartshop.com.au, dartshopS.com.au and darts.net all have an account with G and then all bid via adwords....meaning you can refrain from bidding too high and eventually get the top bids down, reducing cost, whilst having 3 bites at the cherry.
It isn't going to bring bids down, the result will be an overall higher CTR with a higher CPC as well because you'll be bidding against yourself. It is a way of paying more to try and competition out.
Interesting concept and i cant see how G can stop 3 legitimate websites all having an account and all bidding in the same field. Lets assume you had a partner in each domain, then wouldnt that be a restraint of trade?
This is called trying to find a loophole, wouldn't expect Google to be kind if they detect it.