User-space hashed folder name should be different for a new installation in the same place

When a version of Jalview is installed in (e.g. the default) location and subsequently run by a user, getdown copies all the updatable files from the installation location into a user-space location that includes a folder
Jalview-Desktop/Jalview/bb307bce
The bb307bce is a hash of the installation folder (of getdown), in this case of "/Applications/Jalview.app/Contents/Resources/app".
This folder contains updates to Jalview, but can also contain old files if you switch to an archive channel using the published JVL files.
If there is subsequently a problem with Jalview, you might want to re-install Jalview, quite likely into the same location as the previous installation.
This means the hashed folder will be the same and launching Jalview will still launch the user-space archive version of Jalview, which would probably not be expected.
NOTE: that the newer version of getdown-launcher.jar will still be used. Initially the installation getdown-launcher.jar is used, which compares its version with the one in user-space (if there is one), and either carries on with the launch if itself is newer, or relaunches with the user-space one if that one is newer.

In this case the user can just delete the Jalview-Desktop/Jalview location of the user-space updates (this varies from platform to platform and might be customised), but it isn't obvious to do this.