Why are there multiple versions of pdfium.dll in my application folders?

It caused me problems when publishing my MVC .net application (project) to the web server. They were published to the opposite folder. I had to manually re-copy these files to the appropriate folder to match my project folder structure.

Project folder/x86/pdfium.dll date of: 2/15/2022 size: 10,232KB
Project folder/bin/x86/pdfium.dll date of: 4/8/2018 size: 13,315KB