goodroi - 4:17 pm on Apr 23, 2013 (gmt 0)
Duplicate meta descriptions happens alot more often than you would think. Once reason for this is people install multiple seo plugins into their CMS. I recently had to clean up a wordpress blog that had 3 meta descriptions from 3 different plugins that were added over time and never cleaned up.
Best case scenario is that Google just ignores the extra meta data but that is still hurting your rankings? How? Well you have wasted a good amount of time working on something that isn't helping your site rank higher. In extreme cases it can even slow down sites (think multiple big & redundant descriptions on a mobile site).