SEM Question – Can you have two different campaigns appear on the same SERP?

I have two different campaigns with AdWords and some of the campaigns have overlapping keywords. Each campaign is for a different website. If a user searches for that keyword is it possible for both ads to appear on the same page, or will only 1 ad appear at a time?
Also – if it’s not possible for this to happen, how can I make it to have two ads appear on the same search results page? What’s the best way?

I’m guessing that google limits displayed ads to 1 per account, otherwise someone could push out the competition by taking all 12 page one positions.

I have heard that the accumulated quality score for a given keyword applies to all campaigns. Suggesting bad ads on one campaign getting poor ctr would effect a winning campaign sharing the same keyword.