How does google handle targeting the same placements within an account? Can I do this per campaign? per ad group? per domain? I don't want traffic to be split between ads from one campaign and ads from another that are targeting the same placement...
you can use this by camaign or per ad group choose add placment and set cpc for each placment and if you have placment Avg position more than 3 you have to increase your bids!
So your saying that either by campaign or ad group I can target the same placements, and they won't interfere with one another? Google won't split traffic or anything like that?
It's always better to have only one version of a keyword or placement in your account. This prevents from confusing Adwords although I believe it will rotate between them but it may not be an even split. It should still depend on your ad's quality. The higher quality one will tend to show more often.
Thanks Lucid... so if I wanted to have multiple ads on the same placement, you would recommend running them on seperate accounts? Could these be separate accounts within one MCC?
No. Do it from one account as you can have only one account. Even with two accounts, only one ad would show for the same domain. Your ads will be split regardless. It's called split testing your ads to find out which is best.
I don't mean split testing, I have two totally different campaigns, different domains, everything... but I want to advertise on the same placements, without one effecting the other in terms of delivery.
From one account, I don't believe that would be possible. It's one ad per placement allowed at one time per account. That's the way the system is set up. From another account, that would be against the TOS and get you in really big trouble. So don't do it.