We run some of our website’s ads directly through AdSense, meaning we have AdSense tags embedded on pages. Our other ads are trafficked through DFP Small Business with AdSense line items targeting all the DFP ad units. The DFP ad units are implemented using Google Publisher Tags (GPTs) on the corresponding web pages.

For those ad units trafficked through DFP we have one corresponding ad unit defined in AdSense. In each case the AdSense line items in DFP only target the DFP ad units with their corresponding ad unit in AdSense. In other words ad unit A in DFP has a matching ad unit A in AdSense and all DFP line items targeting ad unit A with AdSense creatives use AdSense ad unit A as their only creative. Additionally, the AdSense ad unit A is only trafficked through DFP.

Recently we’ve seen the number of Ad Requests reported by AdSense rising for the ad units trafficked through DFP but not for the other ad units. For the same time period Google Analytics does not show an increase in traffic. It is now to the point where some of the ad units trafficked through DFP show more ad requests in AdSense than the Total Impressions reported through DFP. We are only seeing this behavior for the AdSense ad units being trafficked through DFP. The ad units served directly through AdSense tags have been reporting a steady number of ad requests.

Here’s an example from February 18, 2015.

Analytics reports a total of 82,000 page views.

DFP reports ad unit A had 21,000 total impressions with 5,400 being served by AdSense and the rest being served by other ad networks.

AdSense shows the ad unit A had 124,000 impressions. That’s more than the total number of page views and ad unit A only appears on one page of our website. It’s also more than 5 times as many impressions as DFP shows across all networks.

I’ve checked the rendered web pages and don’t see any ad units duplicated.

Does anybody know how the AdSense ad requests could be higher than the DFP total impressions for an ad unit that is only trafficked through DFP?