How can I *include* duplicate Posts with FWP?

Is there a way to allow duplicate posts from different sites, but not from the same site? I know most people want to eliminate them, but I am getting the “duplicate of an existing post” error in my diagnostics. I would like to actually include duplicates. Is there a way to do that?

For example, if Site A, Site B, and Site C all have the same Post, I want to syndicate all 3 Posts from all 3 sites. Currently FWP only syndicates Site A and then thinks Site B and Site C are duplicates.

In In syndicatedpost.class.php I changed this:
$this->_freshness = 0; // Same old, same old
to this:
$this->_freshness = 2; // Same old, same old

But it then syndicates all posts from all sites continuously each time. So it does accept the same Post from Site A, Site B, and Site C, but then 60 minutes later it syndicates again and now I have 2 Posts from Site A, 2 Posts from Site B, and 2 Posts from Site C. Then 60 minutes later I have 3 Posts from each site… Is there a way for me to tweak so it does not get duplicates from the *same* site?

http://wordpress.org/plugins/feedwordpress/