Higher resolution Pixiv images

The following images are not duplicates. These are higher resolution Pixiv images.

Image 1: https://danbooru.donmai.us/posts/4861914?q=parent%3A4853204

Image 2: https://danbooru.donmai.us/posts/4861913?q=parent%3A4853218

Do me the great favor of approving them.
Thank you for your time.

If they are tagged as Pixel perfect duplicate, it's a Bot who did that, which was programmed by nonamethanks. The Bit checks if images are pixel perfect, so you can assume that it is just a dupe and not of higher quality.
Filesize doesn't determine if an image is of higher quality or not.

I understand.
Is there something that I have to take into account to prevent this from happening again?

If you use the upload bookmarklet it'll check for similar images automatically before you submit the upload. If the filesize/resolution are nearly identical, there's a good chance they're pixel-perfect duplicates and you should avoid them.