Are you sure it's a scam? I listened to the vmail and it sounds authentic. Nothing untoward. Actually tells you to check the official website for Duke-Progress if the storm brings power outages. Nothing else.
I believe you are correct. Even the Cheraw Police department lists this number on their facebook page as the number to call for information during this hurricane season. It is always possible that someone spoofed the number and that those posters who say it is a scam received a different call but it is highly likely that this is the Duke energy phone number. The fact that they tell you to check the website is further evidence that it is in fact Duke energy.