The two charges are a result from a request you have made; for ex: adding, deleting, merging orders, etc...What happens is when you originally place an order for the amount of $XX and you email us and wanted something added and the new total comes to $XY; the original authorization for $XX is on the card (a temporary reserve on funds) but when the revised order ships, it charges the card for $XY.
Our new system allows us to place an authorization on your card (similar to pay at pump gas stations) without "actually charging" the card. This means that when you place an order, Verisign places a temporary hold for that amount to ensure the card is valid and the funds are there...this does NOT actually take the funds out. Once the order ships, the funds are withdrawn (called a delayed capture). Now when the revised order is shipped, the system charges the different amount to your card, and the authorization will drop off within a couple business days (depending on your bank). I know this is kind of confusing, but it works out best for the customer and for us because it ensures the funds are not taken out until the order is shipped. Oh, and also to clarify, this should not cause overdrafts because the funds are not taken out of your account just temporarily put on hold.
Hope this clarifies any confusion.