Will this be treated as duplicate content?

I believe some time ago that Matt Cutts addressed this very issue because of the way typical blogs work -- where the home page provides a summary of recent posts. His stance was that Google does not count this against you. Google's own blogspot platform works this way by default, so it looks like you're A-OK on that part. So moving the intros to the home page only was a smart thing to do.

But if it's possible, you might want to shorten that "half" to "a third" just to be safe.

Indeed. I got request to remove a paragraph on a page, because very similar paragraph was on another page. And I got this from a established and well-known SEO company.

If you pay attention to any blogs, many of the big names are carrying the same stale sales pitches thorough their sites. Doesn't seem to hurt them. And as other user posted above, Cutts says it's perfectly fine.

Now, the issue at hand. I would not have exact same pages on the site. SEO is not even my first consideration, but keeping the structure tidy, and not confusing visitors or maintainers.

I'm not sure which platform are you using, but most decent CMSes allow you to create custom links to the navi. I've done something like this in WordPress and a few other systems by just adding a custom link as the first sub menu link.

If you can't do that, my second suggestion would be either jQuery (child's play to create extra navi item that only users can see) or redirect (technically add an extra page, but redirect everyone back to the real page). This last one is not optimal from SEO perspective, but you've missed the best suggestions already. Edit the menu if you can.

Thanks so much for all of those replies. Nothing like such universal agreement!

Several people asked why the need for two intros exist. That's worth answering.

My site has two sections, a line of related products for sale and reviews of equipment that works with those products.The home page has intros/overviews of each section in addition to a minor amount of other content. Each section then repeats the individual intro/overview.

SEO activity does not focus on any of these pages. The individual product and review pages are the SEO landing pages. However, many people will enter the site through the intro pages, and others will enter through the home page. The intent is to orient site visitors immediately.

Do they have the 50/50 ratio, like the problem mentioned in the thread?

If you see Google home page, from the home page, you will be able to visit Google's all the pages, sections, products or services. And it is very user friendly and you can't call Google a foolish company.

The thing is if it is repeated on most of the pages, we should just create a page for that duplicate content and let the page/link be an item of menu.

To be honest, I've never come across a website (legitimate that is) with so much duplicated content.

Whats the percentage? I'm assuming if you have 1,100 words of duplicated content it's a high percentage of the words on the page.
If thats the case, then yes, using a rel="canonical" link would be your best option as Google will only show one of the pages in it's serp's, so you might as well tell google which one to show.