I had recently updated my instalation of Dynamics NAV 2013 R2 to version 7.10.37563. After the upgrade when I run an object from Object Designer it goes always open another RTC instance instead of open that object in my current RTC instance that I already has opened.
In order for the Client to use the existing Client instance it needs to find a Client process with the same COM Interface.
Some changes were made to the Client COM registration to support side-by-side installations. These require some manual steps.
You can read more about it here:
Installing Microsoft Dynamics NAV 2013 R2 side-by-side with Microsoft Dynamics NAV 2013 http://blogs.msdn.com/b/nav/archive/2014/02/24/installing-microsoft-dynamics-nav-2013-r2-side-by-side-with-microsoft-dynamics-nav-2013.aspx
I hope this helps.
That blog is discussing a side-by-side install with 2013. I believe this original poster is talking about a strictly R2 install. As I am having the same issues. But earlier builds of R2 worked fine. I am on build 36897