Hi,
Same thing happened to me: got charged twice for Lion and Lion Server.
I got the following reply from Apple:
"I understand that you purchased Lion and the Lion Server twice. I can certainly appreciate how eager you must be to be refunded, and I would be more than happy to help you with this today.
After reviewing your case, we determined that issuing a refund for the unintentional purchase of "OS X Lion and OS X Lion Server" is an appropriate exception to the App Store Terms and Conditions, which state that all sales are final. In five to seven business days, a credit should post to the credit card that appears on your receipt.
To prevent accidental purchases, sign out of the App Store until you want to purchase an app. To sign out, click the Store menu, then choose Sign Out."