14.04 with GTK+3 and GTK+2

[cscj01]

I am on Ubuntu 14.04.1 x64 running Gnome Flashback (Metacity) after an upgrade fron 12.04.5 where I was running Gnome Classic. I have both GTK+2 and GTK+3 installed. Should I have them both installed, and if so, can this situation cause any issues? If not, which should I remove?

Thanks for the help.