Multiple urls of same node This seems duplicate content, how can i  send a header 410 for the incorrect version of the url and make sure only the correct url is used on the whole website.

This is the original URL: http://www.traveldudes.org/node/2504/
This is the alias: http://www.traveldudes.org/travel-tips/climate-and-best-time-visit-serengeti-tanzania/2504
But what’s this URL? http://www.traveldudes.org/node/2504/gallery
Or what’s this URL= http://www.traveldudes.org/node/2504/map
There are a couple of easy to use modules that will help you manage your URL aliases.  They include, 


Pathauto
Redirect
Global Redirect


The first two aliases you have sounds like the 'default' ones.  You may have created (or one of the modules you have installed automatically) created the other aliases.

All the same, you can manage your aliases (and re-directs) using the modules I mentioned.