Odd one this, it appears that Ubuntu (13.04) opens more than one instance of Blender 2.68a. One is my default customised layout and the other a default vanilla version. But, and this is the big but, both share the same scene??
If I load in a scene/model, both share the same item - see below…
I’ve used Blender for years and on and off with Ubuntu from time to time, I’ve never seen this before O_o
The version I use is the one from Blender.org (64bit) which is self contained and allows me to use cuda with Nvidia (9600GT) - so I can’t use another method to install blender, such as a PPA or the Software Centre