Style for referring to another footnote?

[BergFulton]

Again for IRN 1009117

Costas' second footnote actually refers to the first footnote. He's written it as
Sale entitled "Tableaux Anciens des maîtres français du XVIIIe siècle". Sold for 660 francs, as per Pierre Rosenberg reference given in [1].

But Elysa drops that "[1]". We could work around that but the way he's done it seems the most natural to me, but we can talk about it.

[workergnome]

Hmm. That makes me nervous. Mostly because if you change it in one, it changes it in the other, but you might not notice that distinction—adding additional information to one, for instance.