The fact that the 9.1 version showed up after the re-install, confirms to me that there was still info on the drive related to your last install.
The fact that all is working fine now is all that matters.
For future re-install search w google for a fs9 uninstall tool. After performing a regular uninstall of your fs9 you will run that tool, which will remove ant remaining info.
If you are re-installing on an existing hdd, make sure to format the drive before installing anything back on it. Reason for that is that when deleting files from the drive, they are actually still on the drive, but unable to be seen. Formatting the drive will take care of that (really erasing the drive would require specific software!).
Also, installing FS in a folder wit ha different folder name can be a resolution.
For now I wish you a Happy New Year, and lot's of fun flying hours.
Manfredc3