Multiple Domain Mapping -> Duplicate Content

I'm using the Domain Mapping plugin and would like to enable the Multi-Domains feature.

In wp-config.php I have added the following line:

define('DOMAINMAPPING_ALLOWMULTI', true);

Now it is possible to add multiple domains to a single blog (e.g. example.com and example.net). But there is no way to select a primary domain, so there is no redirect and search engines will recognize duplicate content.

Is there a solution for this issue? In "WordPress MU Domain Mapping" Plugin it's possible to mark one domain as primary and all other domains are redirected to this one. How to do that with WPMU DEV Domain Mapping Plugin?

Thanks a lot in advance!