Exported the same video twice with the same settings yields files with different hashes
Yes, your observation is correct and everything works fine. Even if settings are identitcal, the file hashes will always be different.
The reason is quite simple: XMP metadata which is embedded in the files.
Such metadata entries which are often different are:

time stamps (not only the date but the time too)

creation date
modified date
metadata date


IDs

document ID
instance ID
original document ID



A bit of binary data in the header is different too. All the rest, meaning the actual video and audio data is the same. The encoding algorithms are working deterministic - that means, given the same input they produce the same output. At least those I've tried for my example. This doesn't have to be true in other cases.