This is not a regression bug.It happened in 2.1.2 Studio.
1.Install Titanium Studio 18.104.22.168211301903 build.
2.Click on Titanium Studio icon available on Windows 7 desktop.
3.Select a workspace and launch Titanium Studio.
4.After the launch of Studio again go to Desktop and click on Titanium Studio icon.
5.This time select a different workspace from Step 3.
6.If any update is available , update your Studio to that build .
7.After restarting , check the studio version.
Studio has opened two instances of different version on the same Windows 7 machine .