I've seen stats form a similar website - I've never thought that so many people are looking for phone numbers - it's incredible.
Now getting to the point, in my personal opinion you should do nothing.
Especially don't remove those pages as that's suicide.
Even if the SeoMoz tool is showing duplicate content issues on the site - duplicate content within your site is NEVER a penalty situation. You will never get in trouble for having the same content or similar content on more pages within your site.
The only down side is that duplicate pages will compete to each other in search results but in your case they won't as you are looking for a single keyword for each page (with or without comments on it - the exact phone number that is).
The main goal is to get to a page after looking for that particular phone number so in your case multiple pages from your site with similar content won't compete - you are safe from all points of view.
You should never remove the pages with no comments from the site as it will drop your organic # by a lot - I've seen stats from a similar website and, like in your case, only a few pages had comments/names and 90% were blank pages with the number in h1 on the top only and those pages received a lot of organic direct hits.
The bounce rate however was high - so you might want to give some extra options within that page beside the number and the form as this can even increase your adsense ctr if done with extra care. If you already have a lot of traffic I would suggest A/B testing for the empty pages.