We've heard from many backers with a "recurring payment" or credit card account being charged twice issue. We've reached out to Kickstarter and this is their reply:
"Thanks for reaching out and apologies for any confusion! Backers are not charged for their pledge until the moment a project ends at or above its goal. It's likely that some of these backers are actually seeing the temporary authorization of funds, which allowed us to charge their card for their pledge at the project deadline. This authorization will drop normally after a few days."
"Furthermore, some pledges might be listed as a "recurring" charge on some statements because we do not actually charge backers until a later date. They will only be charged once for your pledge. If they have any questions or concerns, they are more than welcome to reach out to us through our contact form: https://www.kickstarter.com/contact?ref=footer
For backers with a "failed" or "dropped" status, please PM or email us for further instructions.