That’s right, that’s how it works if you’re currently in a release version.
Beta versions will check for beta update notices and release versions will check for release update notices. When downloading the update, betas will download the newest beta and release versions will download the newest release version.
Pressing Alt or Option will switch the downloaded plugin between release and beta. If there is no corresponding beta version to download, you’ll probably get a “File not found” error in your browser.