Occasionally, businesses will charge prepaid cards double the amount of the service, then refund one of the charges. This especially happens often with recurring billing businesses, such as Spotify. Because the charges are both in the "authorization" state (not converted to transaction), the second charge is refunded quickly. Usually same day, or the first business day.
Businesses do this as part of their risk evaluation for a user with a prepaid card. Their concern is that the card just has exactly the amount of the cost of the service on it. For example, one month.
If the card gets charged twice, they can be more confident that the user is an actual user of the card, and isn't just planning to use it for a month, or trial churning.