Double Serving Ads from Yahoo and MSN Adcenter

I don't dare touch Google, with all the bans going around.

But I consider Yahoo and MSN disposable, and I can live with a temporary ban from one or both of those.

I have two websites, one selling widgets from ACME, the other selling widgets from ACE. I am advertising on the term widgets. Customer ussually swear by ACE widgets or ACME widgits, and competition is light to nonexistant.

For MSN and Yahoo, do I need two accounts for this, or can I double serve from one account if the websites are different.