Somehow I was charged twice on for my Avast Pro. How do I get this fixed?
Contact support: https://support.avast.com/en-us/contact/
Please, keep in mind that they can take a few days to handle your situation.
You can take a look here: https://support.avast.com/en-us/article/24/ (Order Processing > What can I do if my order is duplicated?)
Good luck! 
Request a refund:
https://support.avast.com/en-us/contact/sales_refund/