Will I be charged extra for pre-ordering an album that has already released a few songs?

I pre-ordered an album for $18, and the album already had a few songs released on it. It seems that I received these songs instantly, but I also paid for them separately, which as most know, is more expensive than buying a full album. Does this mean that an additional $18 will be deducted from my account even though I've already paid for those separate few songs, and will I be charged for each song that releases up till the release date of the album?

I just thought I was paying $18, but now it looks like I'm paying more.

Thanks for your help! 🙂