Google maintains a high standard for our user experience and the quality of our advertising. In order to preserve the quality and diversity of ads running on Google, we don't allow advertisers or affiliates to have any of the following:
Ads across multiple accounts for the same or similar businesses.
Ads across multiple accounts triggered by the same or similar keywords.
Individuals advertising for themselves or for their own businesses may only have a
single AdWords account. However, your account may contain multiple Ad Groups and ads triggered by the same or similar keywords.
Only client managers (such as third parties or search engine marketers) who use a My Client Center can have multiple AdWords accounts.