Google Adsense when it should be Chitika

I'm using Chitika for the first time and have a question. There are times when  I look at my page and, instead of Chitika, I see Google Adsense ads. Is this normal?

Since we have an impression-share system on Wizzley, half of the time your ad ID (Chitika) is shown, and half of the time our ad ID (Adsense). Keep reloading the page until your ID shows up. It's all in good order.

OK, that explains it. Thank you. I was just making sure I didn't do something wrong.