Thanks for your question. The reason is that we show only unique impressions to advertisers (i. e. globally unique IPs for the whole network during 24h period). You can see non-unique impressions here:
You can run as many ads on the same page as you want. Embedding several ad units on the same page should somehow increase your income, but not much.
Ideally more ads you have -> more buyers you attract to advertisers -> more income you have. Absolute amount of unique impressions should not be relevant.
But it works only when both conditions are satisfied:
1) publishers send buyers to advertisers.
2) advertisers pay per sale.
Currently it is not the case. According to
current stats only <10% of earnings come from goals.
So currently we need to distribute significant part of money paid by advertisers somehow, and we use a number of globally unique impressions as one of the important criteria.
I know we need to document all this in detail. We are working to attract more advertisers that pay per sale. We offer discounts and free integration with our
Goal Tracking API to such advertisers.