Strange/wrong/very high or unknown impressions/clicks are usually caused by bots/robots crawling your website. We do our best to filter most of the popular bots but we certainly don’t know them all. Bots can visit your website a lot and they will track statistics just like anyone else.
Plugin statistics are different than the stats on Google Analytics.
Google has much more technology to filter bots, robots and web crawlers then we do so it’s possible their stats may look different as they do filter other things then our system. also, Google is tracking your page views which is not the same as banner impressions, another reason stats by Google will be different.
If you know what bots or IP’s are causing the high impressions you can manually block them under the AD Dashboard Statistics Settings.