I'm trying to make an EPUB book with two "parallel" sets of endnotes. The content itself is an old book, and the two sets of endnotes are supposed to be commentaries/annotations from two different literary critics.

Ideally, the EPUB should look something like this:

So far I've figured out how to convert a list of markdown files with notes into an EPUB like this:

chapter1.md

# Chapter 1

Hello world[^1].

[^1]: Foo.

chapter2.md

# Chapter 2

Lorem ipsum[^2].

[^2]: Bar.

title.txt

---
title: My book
author: My name
language: en-US
...

and running pandoc -o book.epub title.txt chapter1.md chapter2.md.

Still, this is just one list of notes, and if I try:

Lorem ipsum[^a1] dolor sit[^b1] amet.

[^a1]: Foo.

[^b1]: Bar.

then [^a1] gets numbered as 1, and [^b1] as 2.

If possible I'd like to stick with markdown files, just because they're a little easier to work with. If it's possible to style the two sets of notes differently with CSS, I'd like to look into that too.

Appreciate any help in advance.