[EDIT: The page I'm referring to that hosts the ads is NSFW. Just an FYI.]

So, comprehension question here:

I have two ad units #312 and #1229 that are active on my page. One is a horizontal banner and one is a tower. Both are active on the site, but looking at these links:
https://a-ads.com/catalog?ad_unit_id=1229&target_type=AdUnit&partner=1229
https://a-ads.com/catalog?ad_unit_id=312&target_type=AdUnit&partner=312

The number of impressions is drastically different. Am I doing something wrong in my implementation? Should I not be running two different types of ads on the same page? If so, which one would be the more advantageous one to keep?