Duplicate content is not always bad for your site. If users expect to see the information on your site, or your site would be better for users with the duplicate information, then by all means, put it on the site. The legitimate use of duplicate content with permission from the original author is called "content syndication". Google is generally fine with content syndication when it is implemented correctly.
When you use syndicated content, mitigate any possible penalties by using one or more of these methods:
- Provide a deep link to the original source
- Provide additional commentary, reviews, or information such that a user would be better off seeing your expanded version of the content than the original
- Use robots noindex or robots.txt to keep Google from indexing the content
- Write the content into the page using AJAX or an IFrame such that Googlebot can't crawl that part of the page (use robots.txt for the url that actualy has the content which is fetched by AJAX.)
- Don't republish content without permission.
- Don't power a significant portion of a site using duplicate content. Duplicate content shouldn't be any more than 30% of your site. No more than 10% of your content should come from any single source.
- Don't show content that your users don't find useful. Pay attention to bounce rate and remove content that users don't actually read. If searchers land on duplicate content on your site and immediately bounce back to Google, Google will quickly label your site a "scraper site".
- Don't let users post content with no review. Some users will try to post content that is duplicate and spammy. Make sure you can detect when this happens and take it down.
In the case of the brochure: Publish it on your website. One page of duplicate content won't hurt much as long as there are other original pages on the site. Use one of the methods of mitigating any penalties. I'd say the robots.txt or link to the original would be my preferred options in that case.
In the case of the same page on two websites: One page shouldn't make much difference. If a significant number of the pages are the same between the two sites, Google will generally choose to index just one of the sites. It may not be the one which you would prefer. Google might choose not to index any of the original content that is on the site that it excludes from the index.