duplicate software downloads

It probably wasn't an identical version. They often release several patches with the same major version number, but the build number increments as they fix minor issues.

Snarky rephrasing:
Tesla, please take me off the list to get firmware in the early group. I'd prefer to wait until the last "dot release" of a given version. Or better yet, when a new major version is coming out only then send me the last "dot release" of the preceding version.

I should be so lucky. One option is that when you get something such as 6.0 in the first place, don't schedule an install. At least I'm assuming that's how it works since I never got an upgrade. Then if there's a maintenance release, you can install it. If you want to read up on reported bugs or issues that people discuss in the forum, you can do that. But I don't think many Tesla owners fear being early adopters.

I don't think anybody with the new hardware is likely to get any version of 6.x until the new features are released. Then it's a matter of what comes up based on feedback to the mother ship, or reports from users, so I'd expect maintenance releases with no announced changes.