Is it possible to have installed both versions of Unity at the same time, without any problems?
I’m having some problems after upgrading my project to Unity 3 trial, and I’d like to keep developing it in Unity 2.6 while still being able to play with Unity 3 on another projects (I have a backup of the project).
As JRavey says, just install the two versions to two different directories. If you’re using Windows, just change the directory during the installation process. If you’re using a Mac, the installer installs into a folder named “Unity” so you’ll need to rename it after the installation process has finished. Be sure to also keep your projects separate. Once you open a project in 3.x you will no longer be able to open it in 2.6.1.
I didn’t tryied myself because a friend of mine said to have tried to install into different directories and it didn’t work. He tried to install in a different driver and had no success too.