comma delineation of consecutive endnotes

Manual solution

An admittedly not very comfortable solution is doing it manually, for example with KOMA-Script's multiplefootnoteseparator:

documentclass{scrartcl}
usepackage{endnotes}
letfootnote=endnote

begin{document}

Comma delineation of consecutive footnotes fails upon conversion to
endnotesfootnote{First note.}multiplefootnoteseparatorfootnote{Second
  note.}.

theendnotes

end{document}

Or with a standard class something like this:

documentclass{article}
newcommand*multiplefootnoteseparator{%
  textsuperscript{multfootsep}nobreak
}
newcommand*multfootsep{,}
usepackage{endnotes}
letfootnote=endnote

begin{document}

Comma delineation of consecutive footnotes fails upon conversion to
endnotesfootnote{First note.}multiplefootnoteseparatorfootnote{Second
  note.}.

theendnotes

end{document}

The package scrextend may also be loaded to integrate KOMA-Script's multiplefootnoteseparator in standard classes.

Automatic Solution

My package fnpct offers a different solution. If loaded together with the endnotes “it just works”:

documentclass{article}
usepackage{endnotes}
usepackage{fnpct}

begin{document}

Comma delineation of consecutive footnotes fails upon conversion to
endnotesendnote{First note.}endnote{Second note.}.  theendnotes

end{document}

fnpct also reverses the fullstop and the footnote markers but that can be changed with a package option.

documentclass{article}
usepackage{endnotes}
letfootnoteendnote
usepackage{fnpct}
setfnpct{reverse,before-punct-space=0pt}

begin{document}

Comma delineation of consecutive footnotes fails upon conversion to
endnotesfootnote{First note.}footnote{Second note.}.

theendnotes

end{document}

I had a similar problem and the footmisc package did not work. I did the following

footnote{note1}vphantom{d}$^{text{,}}$footnote{note2}

It's quick and dirty but it worked.