Two times upgrade paid for Icloud

1.

Then you also have received 2 x invoice from Apple.

Each invoice has its own order number and document number.

Scroll down on the invoice and read:

If you have any questions about your bill, contact support. This email confirms payment for the iCloud+ plan listed above. You will be billed each plan period until you cancel by downgrading to the free storage plan from your iOS device, Mac or PC.

You may contact Apple for a full refund within 15 days of a monthly subscription upgrade or within 45 days of a yearly payment. Partial refunds are available where required by law.

You have the option to stop receiving email receipts for your subscription renewals. If you have opted out, you can still view your receipts in your account under Purchase History. To manage receipts or to opt in again, go to Account Settings.

2.

If you have upgraded iCloud storage, it would take about 1 to 3 business days in order to process.

Once your request for iCloud+ has been activated, you should receive an invoice in your email box.

Check -> Go to -> Settings -> your name -> iCloud -> if you see 50 GB (or 200 GB or 2 TB) then you have an iCloud subscription.

If you have an iCloud subscription, you will receive a monthly bill from Apple, check your email box.

You pay monthly for iCloud storage.

How to use iCloud on iPhone -> How to use iCloud on iPhone – Apple Support (UK)

What do you mean you paid 2 times? You cannot subscribed to the same iCloud storage twice.

You subscribe once, but it's charged every month, as it's a recurring rental of space. You will only have access to it while you are paying for it.

You could have upgraded to one storage capacity and then upgraded to another capacity larger than the one you currently had.

Also, what happens when you go to Settings ➜ Account (top of settings) ➜ iCloud on your iPhone? How much storage does it say you have there?

Do note, iCloud storage does not in any way affect your iPhone's local storage capacity.