Didn't work (for me at least).
After installing Sins (incl. the unwanted Entrechment) there is only one icon for Entrechment. None for Sins vanilla, just like Pako75 said. Uninstalling only works by deleting the gamefolder, as there is this 28,8 XML error.
After deleting the game and restarting Impulse there are two icons again. One for vanilla and one for Entrechment. But it doesn't matter, which one I choose to install. As soon as it's finished, there is only the Entrechment icon left and the beta was installed again. Not even removing my Entrechment serial from Impulse worked :/
I could semi-fix it by installing the Sins standalone version, but that's not really the best solution obviously