PowerPress has no "auto syndicate" features that allow it post to multiple sites like you're looking for. The only solution really is to just manually add it to both sites. It's possible that there may be a third-party WordPress plugin that does this, but if it exists, I've not heard of it.
I'm no SEO expert, but it's generally considered to be a bad idea to publish exact duplicate posts on multiple sites. Theory is that search engines will assume one site is scraping the other, and potentially lower both sites' search engine rank. You could consider leaving the complete show notes for the podcasts on the site you want to drive traffic to. And then when you post the podcast to the other site, just put a short note with a link that says something like "for complete show notes, click here." The link would go to that same episode's post on the site you want to drive traffic to.