Only one version of Boris FX Continuum plugins can be installed for Vegas Pro at any one time. So, if you have an older version of Vegas with legacy Continuum plugins, these will be replaced with the newer versions that ship with Vegas Pro 19/20. We highly recommend uninstalling any existing Boris FX plugins previously installed on your system to avoid problems. To do this, right-click the Start button and click Control Panel. Go to Programs and Features (if your Control Panel is in Category view, go to Uninstall a Program). Find Boris FX Continuum, click to select it, and then click Uninstall.
However, if you want to keep your older Boris FX plugins, then you do not install these current products as they will overwrite any older plugins.