Unfortunately I don't know what is checksum so I don't know how to check it?
A checksum is unique number/string for a file that's calculated based on the file's contents. This is a method to ensure you have the a correct file, regardless of filename.
Use 7zip to get a CRC/SHA checksum of the file - https://www.blogsolute.com/7-less-known-features-of-7zip/26665/. Compare it to the official SMB ROM checksum from Tosec/No-Intro - if it's not a match, you have a hacked/modified ROM file and that's the reason the emulators behave differently.