Welcome to the Spotify Community and thanks for posting about this.
Since you're mentioning that you paid for Premium twice during the same month, it'd be good for you to take a look at this support site article.
Make sure to carefully read through the 'Do you have more than one Premium account?' section under 'More help'.
These steps should definitely help you out with finding and blocking the source of such unexpected charges.
Suggesting this since, in your case, it looks like the charges might likely depend on having accidentally activated Premium on more than one Spotify account, each time with a different payment method.
It'd also be good to quickly double-check with the provider of each of the mentioned payment methods whether the charges are actually confirmed or they're, for example, pending or even the outcome of a 'pre-authorization' test.
Hope you'll find this useful. Keep us posted if there's anything else we can help with!
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