Well, the answer would be yes and no. A robots.txt file would stop the bots from indexing the page, but links from other pages in site to that non indexed page could therefor make it crawlable and then indexed. AS posted in google webmaster tools here:

"You need a robots.txt file only if your site includes content that you don't want search engines to index. If you want search engines to index everything in your site, you don't need a robots.txt file (not even an empty one).

While Google won't crawl or index the content of pages blocked by robots.txt, we may still index the URLs if we find them on other pages on the web. As a result, the URL of the page and, potentially, other publicly available information such as anchor text in links to the site, or the title from the Open Directory Project (www.dmoz.org), can appear in Google search results."

I think the best way to avoid any conflict is applying the rel="canonical"  tag to each duplicate page that you don't want indexed.

You can find more info on rel canonical here

Hope this helps out some.

We worked on a website that sells silicone wristbands. Not an exciting product anymore by any means. What we did to help create a buzz was partner with various awareness causes during a given month and posted polls and funds raised results on landing pages. Then we had the awareness cause we worked with link to those landing pages where visitors can see the amount of money raised, read more info about the cause and even place an order to support the cause.

If client has a mailing list of any significant size, you can send out email blasts offering discounts, free upgrades or other incentives that are further explained on landing pages and build traffic and possibly links to that page as well.

Im also looking forward to hearing some strategies others may have to offer.

Bilal, since you already have one at the top of google why not come up with a different strategy to try and get the second site moving up in google rankings? Sounds like it cold be a good springboard to try some experimentation in optimizing for better ranking.

Unless your simply wanting to merge the sites and concentrate solely on the one site.