Don't display the same ad twice on the same page

Maybe this has been answered elsewhere, but had not seen in my searches. I'm sure many of you are aware, AdSense limits a page to having no more than three ads posted. I'm combining AdSense with a couple of other ads from another provider. I'd like to be able to post random ads in various blocks on the page, but how do I ensure no more than three AdSense ads are shown?

For example say I have one leaderboard ad, three ads on the sidebar and one ad in the footer. Each of the five blocks can randomly select from a group of 10 ads, of which five are AdSense and 5 are not. Other than doing something programmatically, is there a way in the ad module to have it be "smart enough" to not pick from AdSense after the allotment of 3 has been met?