Having 2 versions of a site, how to not get one spidered

Non SE friendly and SEO site

[epadgett]

For a product line my company is going to be running there is going to be a very "flashy" non Spider friendly version of a site. The storefront site if you will. On the same URL (different directory) we are wanting to have a SEO site that is made for organic search.

Are their penalities if somehow both sites get spidered? Both versions of the site are going to have similar content and similar copy, i dont want to get us in trouble for any type of spamming or exploiting.

Thanks!

(This is the best forum i could think of putting this in, seeing as the solution may be to add the storefront site to the robots.txt.)