Being charged double for light sail instance

Are you sure you are not activating two units?
1,488 Hrs, so it looks like you are running 2 units.

Lightsail plans are billed on an on-demand hourly rate, so you pay only for what you use. For every Lightsail plan you use, we charge you the fixed hourly price, up to the maximum monthly plan cost. Therefore if the bill is for $40, there is a good chance you are running two 4 GB Memory bundle instances. For further questions on billing, please refer to the "Billing and Account Management section" in our FAQ page. https://aws.amazon.com/lightsail/faq/. Please reach out to customer support if you have any questions.