I occasionally clobber whatever I had already copied to the clipboard. It would rock to just be able to keep all of my clipboard history right in front of me.
I use Parcellite. You can install it from Ubuntu repository by doing this command in terminal:
sudo apt install parcellite
Try Glipper, in the repositories. I'm assuming you use Gnome.
I would recommend glippy if you want a clipboard manager that also supports images that were copied.