Consequences in processing H4 and H1 petition simultaneously

Hi, I am currently in H1B visa and my wife is on H4. My wife’s H1b visa is processed thru a consultancy and she has received the receipt number. Meanwhile, my H1b and her H4 visa is expiring on 30 - Jun - 2012. My company has applied for my H1b extension which includes my wife’s H4 extension as well. My wife currently has both H4 and H1b in process. Will there be any consequences in this case? In the context where both the petitions are approved, which one would be valid? Please clarify.

The one that gets approved later. Also, I think it would be based on the date approval goes into effect. You can discuss this w/ your attorney as well.