NOMAD upgrade on USB stick causes double data directories

IBM Lotus NOMAD feature in Lotus Notes 8.5 beta 1 installation on USB stick. Using NOMAD on USB stick 8.5 beta 1 upgrading a previous NOMAD version NOMAD 7.0.3, does not overwrite Lotus/Notes/Data directory but creates a xcopy to the Lotus/Notes/Data/domino directory of the old release 7.0.3 and causes the disk capacity to be doubled. You actually have 2 Data directories on your USB stick. One under the Lotus/Notes/Data (8.5) and one under Lotus/Notes/Data/domino directory (703). Own folder structure is gone and overwritten by upgrade.

Is there a way to fix this without deleting the whole NOMAD installation and use a clean install on your USB stick?

Corrective actions already taken:

Manually delete obsolete data directory.

Other relevant information:

Operating System:

Windows XP version 2002 SP 3.

IBM Lotus Notes 8.5 beta 1.

USB Kingston DataTraveler (2GB) ReadyFlash

Company uses CA and Desktop-Policies in there Domino environment.