Importance:
AWA
AWA says that Google doesn't want more than one ad from the same advertiser to be shown at the same time on the same page.
AdWordsAdvisor Says: [
Link to quote]
In as few words as possible, the bottom line here is that Google strongly believes that one individual should not occupy two spots for a given keyword.
With a limited number of spaces available, this is simply not fair to your competitors - most of whom also want to appear towards the top of the first page.
