The install page has 2 installation options:

Upgrade

The upgrade option will be available if CSVI VirtueMart finds an older installed version. The upgrade option will convert existing templates, log entries and currencies.

Fresh install

The fresh install option is always available. In the fresh install no old settings and/or templates are being converted.

Additionally there are 2 more options that can be chosen:

Remove existing backup tables

During installation CSVI VirtueMart will backup your current tables. It might be that old backup tables exist. Enabling this option will remove the old backup tables before starting the installation.