Is having more than 1 SEO plugin bad for SEO?

Selected answers from the Dumb SEO Questions Facebook & G+ community.

• 
  Melissa Klaver: Good afternoon!
  I'm brand new to WordPress, currently building my first website. I read a lot about essential plugins (especially those pertaining to SEO), and I'm wondering if having more than 1 SEO plugin is bad in any way for the site's SEO? I'm sure it largely depends upon what functions each plugin serves, but is it possible to over optimize with multiple plugins? ;
  
  Thanks in advance!
• 
  Brent Wildman: Yes.
  Having multiple plug ins is bad for load times first of all. But more importantly, when displaying the information which one has priority. They will probably end up over riding each other and confusing Google when they try to crawl your site.
  
  My Favorite one is Yoast, ; http://yoast.com/wordpress/seo/
• 
  W.E. Jonk: Personally I wouldn't say over optimized in SEO sense. But what can happen and frequently does is that multiple plugins serve the same. For example you have multiple og tags. Although this isn't really a problem it can slow down the page speed quite a lot. However if those SEO plugins serve the same tags but with different values then it can be an issue. For example one plugin serves
  
  <meta name="robots" content="index,follow">
  
  while the other serves
  
  <meta name="robots" content="noindex,nofollow">
  
  Then Google will respect the noindex,nofollow one which means that the page is out of the index and will not pass any link value. To investigate which plugin does what makes it much harder to track down the issue and serving the same tag isn't needed to begin with.
  
  So personally I wouldn't install multiple plugins that do the same .
• 
  Raymi Rodriguez: I agree with the above answer, stick to one plugin. If you install multiple plugins they will create a mess on your source and those messes aren't fun to deal with lol
• 
  Warren Chandler: As everyone has says, if one plugin does it all, use that plugin.  ;However, it's important to learn the shortfalls of individual plugins and address those too.  ;
  
  Yoast's plugin for example is very good, but if you have a BuddyPress site it doesn't seem to work as it should (at least it didn't last time I checked).  ;You need to install additional plugins to make up the shortfall.
• 
  Chris Stocker: As mentioned above, the plugins could have different settings and one may want to rewrite titles while the other doesn't and it could lead to more harm than good. You can never go wrong with the Yoast SEO plugin.
• 
  SEO+: Too many plugins are bad for the site load time so should be avoided. You only need one SEO plugin. I've looked at various ones and recommend Yoast
• 
  Unique Websites: I have now switched to using Yoast - I find that it helps my users (many of whom know nothing about SEO) with prompts on writing title/description and also tells them when the keywords in the title don't appear in h1 or first paragraphs etc.
  
  As said above, minimise your plugins to reduce loading times.
• 
  Reginald Chan: +Melissa Klaver Hope thos is not too late. It really depends. Firstly are you experienced enough? Most SEO plugins are offering about the same feature while some offers more options.
  
  Personally, don't get 2 plugins that does the same job. Makes no sense :) However, if plugin A does job one and plugin B does job two, that sounds more 'better'.
  
  Well just my 2 cents and hope this helps.
• 
  Melissa Klaver: Thank you all for your responses! I greatly appreciate the feedback--it has unanimously confirmed my thoughts! ;