†
The second step of the footnote ladder, inherited from the scribes.
After the asterisk, the dagger: the classic sequence of note marks is *, †, ‡ — doubling up when it runs out. The sign descends from the obeli with which the philologists of Alexandria flagged suspect passages.
Beside a name the dagger holds another, more solemn trade: it marks that the person has died. The entity is †; its two-bladed sister, U+2021, is ‡.
Wrong: second note marked with ** (stacked asterisks)
Right: first note with *, second with †, third with ‡