If you notice that you have been double charged, it may be related to the fact that you have Automatic Payments set up via PayPal. 

An example might be that you receive an invoice for hosting services coming up for renewal. You log on and pay the invoice, and receive a transaction ID. But a few days later, you see another charge from Siteocity/Hostbed. The problem is that this second payment, is never logged anywhere within our internal system. It's only shown on our PayPal page.  

What are Automatic Payments in PayPal? - Set up a billing agreement so that merchants can automatically charge your PayPal account for future payments. You can cancel a billing agreement at any time from your PayPal profile.

We strongly recommend that you do NOT set up automatic payments via PayPal. While that might be annoying, it will prevent you from being accidentally charged.