I am broadening the content of my primary website. I will use a new uri which will become the primary. Both the existing and the new uri will share the same home or introductory page. Is this problem for Google and other search engines?
If you have 2 different urls on the same site that have pretty much the same content you have duplicated content for these 2 pages.
If you are listing news on your home page which you archive later on, present it as a blog. Basically a summary of the entry on the home page and then have a different page which contains the full article.