I don't think Google has any illusions that it's the same person. Instead they see it as the same beneficiary. If this weren't a problem we could have a Hacker

I don't think Google has any illusions that it's the same person. Instead they see it as the same beneficiary. If this weren't a problem we could have a Hacker News "free ad" board (with "free" meaning "at the cost of other advertisers". Due to the bid system free ad coupons cost Google next to nothing) where people could post their pet site and hundreds of people could use some or all of their "free" $100 to yield tens of thousands in free ads.