You need to verify your active subscriptions with Apple and cancel any you don't need. In general you cannot be directly charged for the same thing more than once, since you can only ever activate one subscription for a specific service on your Apple ID. You cannot activate a second one, as it would immediately replace the first one.
How do you know the charge you see is from Apple? And if it is from Apple how do you know its for Paramount+?
Apple charges would appear as "apple.com/bill" on your statement only without specifying what its for. If it appears specifically as a Paramount+ charge on your statement, then Apple has nothing to do with it.
You can always verify and cancel your active subscriptions with Apple by following the steps in the support document below.
click here ➜ If you want to cancel a subscription from Apple - Apple Support
If you are the Family Organizer for a Family Sharing group, you will get charged for other Family Members subscriptions. But again, the charge would not identify itself as Paramount+ on your payment method's monthly statement, only as "apple.com/bill" and would not appear on your Apple account, only on the Apple account of the person that initiated the subscription.
If it appears directly as a Paramount+ charge on your statement, then you would need to contact Paramount directly to manage your subscriptions with them, Apple would have nothing to do with that.
If it is a subscription from Apple, the once its successfully canceled by following the steps in the link provided above, you can contact Apple Support directly for a refund by clicking here ➜ Contact Apple Support