Why do I have two Zens?

The image shows two installations of Zen, 1.9b is the original install which I remember installing and another one 1.10.1b which I didn't install. So why is it there? Does Zen keeps backup of itself, like how windows does after a major update?

Another thing I should mention is that I changed the default installation when installing for the first time from C drive to folder in D drive because that's how I like to install programs in my laptop.