Sounds like a “refresh” issue going on. The menu may be updating once but not twice during installation. As I say, I cannot reproduce this.
You could see if this still happens by upgrading to MATE 1.14 in case your system is using the stable MATE 1.12 that comes with Xenial 16.04.
Tip: A reboot isn’t essential. Running the command via ALT+F2 would have saved you running it (then killing it) in a terminal.