Duplicates filtered out of Clipboard history

You could perhaps make a macro based on the idea of pushing to and popping from a stack.

Rather than choose new keystroke triggers, you might reassign Cmd-C/V/X for use with the macro – but be careful, and make the macro active only for this one application if you want to keep your macro as simple as possible.

I have found a forum post from 2016 which is relevant to this idea: Clipboard Stack Macros, by @Lantro. The author has kindly provided a rocking video to demonstrate it in use, too! I have not tried the macro.