You can install 7.0 on the 6.5. Just not select selection upgrade in the installation wizard. So you can have both installed and you can switch from one to another depending on your needs. Databases can be upgraded also during the 7.0 installation. Alternatively you can use 7.0 data import to import 6.5 databases to different lacation in 7.0 form.

Hopefully that will help you!