Apple Music is a monthly subscription, so why was I charged twice in the past week for my subscription!?

Ive been saving money on my card, but now it’s gone, because for some reason I was charged twice in the past 7 days for my monthly Apple Music subscription. I’d like to be refunded for one of those charges, there’s no reason I should be charged twice in one week for my subscription. If this continues, I’ll be canceling my subscription completely. Especially, seeing as Apple Music is supposed to be a monthly subscription.