For SEO purposes, you are probably going to be starting with a tremendous disadvantage.
As the previous posters have mentioned, you are starting off with a lot of duplicate content.
With that said, you can still gain a tremendous amount of value from the mirrored site, how?
By simply thinking outside of the box.
Instead of using SEO, focus more on branding and social media reach.
You'd be surprised as to how much of your company's content may not be found on social media.
If you add on top of this a value-added persona brand, you may be able to drive quite a bit of interest in traffic.
Don't think that just because you're dealing with duplicate content that your marketing efforts are dead in the water.