Question regarding sitemaps and a Wordpress sitemap generator plugin

So I am working on an ecommerce site that has a wordpress blog installed (domain[dot]com/blog) and we have our sitemap for the entire site set up and good to go (domain[dot]com/sitemap.xml). We saw this plugin for Wordpress which automatically updates a sitemap every time the blog is updated and then pings search engines every time we post something new: http://wordpress.org/extend/plugins/google-sitemap-generator/faq/

My question is, since this is a WP plugin, it will be generating a new sitemap at (domain[dot]com/blog/sitemap.xml), so: will that create crawlability issues with search engines since we'd essentially have two distinct sitemaps? Would this negatively effect SEO?