2 or 3 same ad in one adsense banner

what happen?

[danneile]

recently,wide skyscrapers(5 ads) in my some pages show 2 or 3 same ad. all pages in other sites I saw that have wide skyscrapers show 5 different ads or show 1-4 ad(s),other positions show nothing.
so what happen?
thanks

[Jenstar]

Chances are it is multiple affiliates who happen to be running the same ad for an affiliate program or product. If you right click, you should see differences in the URL.

[richmondsteve]

And I am pretty sure affiliate ads need to say "affiliate" or "aff" in them (not that the average user knows what "aff" means).

[danneile]

I use wide skyscrapers,so I am sure that the same ads have the same url.