Upgrade from 6.3 to 7.0 copies all the data from the 6.3 database to the 7.0 database.
This means a new destination database for 7.0 must be defined.
ServerSetup screen "Information about destination database" sets the source database to the one in SuperOffice.ini in the 6.3 server installation folder. After this is checked OK, select the target database for the 7.0 installation.
This can have different username, password and prefix than the original 6.3 database. You can also upgrade from ANSI to Unicode.