Downloading twice 377MB when upgrading

BP-Web

When upgrading from Bitdefender AV plus 2016 to 2017 first a 377MB install file download is started. After this download a previous version of Bitdefender is detected that is de-installed by the installer software. After the reboot again the 377MB install file is downloaded.

I guess that a manual de-install before the upgrade would solve this issue but to me this looks very weird.