Added a second protect plan and charged twice

So back in December 2019 I purchased a stick up cam and signed up for a basic protect plan for it. Now I already had a plan for a ring doorbell which was last renewed for 12 months in July 2019. But now I realise I've been charged for 12 months for both devices when I added the 2nd one in December. Looking at my account the plans for both devices now expire in December 2020I've paid for two full years after only 6 months with the 1st device - not cool. Please help me