Related, I'd also like more than one cursor in a text editor. I believe I recall some Tcl/Tk thing from the mid-90s that had more than one cursor, but I've been unable to find it.
I'm intrigued but a little confused.
Have you ever tried an advanced text editor such as GNU Emacs [1]? GNU Emacs provides a feature that I believe could fulfill your use case. In Emacs, rather than a mere 'clipboard' that holds the most recent thing you copied, you have the 'kill ring'. Anything ever copied to the 'kill ring' can be recalled at any time. You can copy as many things as you want and paste as many times as you want.
I don't use a Mac, so for me the shortcut in Emacs is Ctrl-k to 'kill' text (copy to 'kill ring') and Ctrl-y to 'yank' text back from the 'kill ring'. You can then use Alt-y to cycle through every piece of text that you have 'killed' in your current session. There are further shortcuts to select and copy text to the kill ring. (By default Ctrl-k removes all text on the current line or it removes the current line if the line is blank). Repeated use of Ctrl-k without other commands will grab entire chunks of text that can be brought back with only one Ctrl-y.
Would something like that work for your use case?
Of course with an advanced editor (like GNU Emacs), you have the option to program as many additional shortcuts as you want.