I'm getting close to installing the SWT plugin to replace the Multi-post plugin which I've been using for cross-posting child-blog posts to the main blog. I'm switching in part because I'm concerned about the SEO implications of having duplicate posts. I've heard that this plugin duplicates posts in an SEO friendly manner. So, I'm wondering when I install, should I delete the existing duplicate posts on the main blog, then use the populate function in SWT or should I leave the existing posts? Any thoughts on this? Are the old duplicates a continuing SEO risk?