I’m being charged for Apple Music twice.

Follow the steps here to verify the charges: link-> If you see 'apple.com/bill' on your billing statement - Apple Support

It's unlikely to be for the same thing twice within the same month unless you are the Family Organizer in a Family Sharing group, and somebody else in the family group has subscribed to Apple Music too.

You need to contact Apple Support. Use the Get Support link at the top of the page here.