Avast 8.0.1487 isn’t a final version, the RTM categorisation is incorrect and the notification of its release in the beta sub-forum and beta still being on the UI tends to support that http://forum.avast.com/index.php?topic=122788.0.
So only those with the previous beta version would get this update via the avast UI, those with 8.0.1483 would be informed they have the latest version, which is correct for the regular release version/build.