If your talking about the more google ads on a site yes it can lower your earnings. If you have one set of ads they are the top paying ones for your site. The next set are lower paying. Not sure what question is but i think this might be what they want to know.
I didn't understand your question very well, but your earnings per click depends on: 1. Some keywords are paying more than other. 2. Traffic from USA, UK converts better.
I’m assuming he’s inquiring as to how different Adsense formats effect the amount of revenue you generate per click.