SEO question regarding similar content

I note that if I rank fairly well for longtail keywords a+b+c for a given page, google is far less likely to rank highly another page on my site for those keywords EVEN IF the content is totally different [e.g. a different wedding couple at the same venue on a different day].

How do I extract the maximum value in terms of organic searches that I can in these cases ? As it stands it seems that the content I use to create the second page ranking for a+b+c is wasted if that second page doesn't rank.

Any suggestions from the SEO savvy ?

If your site isn't deemed to be authoritative (lots of links to it; lots of happy searchers who clicked on it in a result and didn't immediately come back), Google's only going to "risk" so much of the SERP listing real estate on pages from it, especially if, in Google's eyes, the two pages are nearly identical.

IMO, your best option is to sculpt the copy on the two pages so they're slightly different. e.g. "spring wedding" vs "summer wedding", intimate vs extravagant. Ideally you'd have some sense of what keywords people are searching for and you could incorporate that into the copy.

Are you confident that the two pages are equal in terms of links, both from other sites and from your own site? Are they of similar age, or is one a wedding from 2010 and one's a wedding from this summer?

You can still get other pages on your website to rank for the same keywords. When you have another page about same venue but different couple it can be made into a completely unique page, content wise.

Search Engine Robots just read the text of your website's html code. You can add a lot of variations to make your page look unique:

1) Use different text describing each page

2) Use multiple pictures and use name each set with unique names

3) Use different external / internal links