Have another look, because it will look as though full amount is deducted but you are only charged for the discounted amount from your PayPal balance or card.
The seller gets the full amount and eBay or PayPal (whom ever offered the voucher) puts in the voucher amount.
You're welcome.
You are not the first, so many people come here asking the same.
And no doubt you won't be the last. 
