The need for more than one series of footnotes is common in critical editions (and other literary criticism), but occasionally arises in other areas.
Of course, the canonical critical edition package, edmac, offers the facility, as does its LaTeX port, the ledmac package.
Multiple ranges of footnotes are offered to LaTeX users by the manyfoot package. The package provides a fair array of presentation options, as well. Another critical edition ednotes package is built upon a basis that includes manyfoot, as its mechanism for multiple sets of footnotes.
The bigfoot package also uses manyfoot as part of its highly sophisticated structure of footnote facilities, which was also designed to support typesetting critical editions.