Doubled root after VII7 · Rules

When the leading-tone seventh goes to I, the tonic chord does not double its root: the second degree rises to the third to avoid parallel fifths.

Doubled root after VII7: When the leading-tone seventh goes to I, the tonic chord does not double its root: the second degree rises to the third to avoid parallel fifths. (Piston, ch. 22, p. 335)