Massenet & his letters = Massenet en toutes lettres : a new biography / by Anne Massenet ; translation by Mary Dibbern. (OCLC #870699448)
This volume’s title page includes a parallel title for only the title proper (“Massenet & his letters”), but not the other title information (“a new biography”). This situation is described in ISBD:
22.214.171.124.2 When a prescribed source of information bears one or more parallel titles, but the statement of other title information is in only one language and script, the other title information, if given, is given
after the last parallel title transcribed.
Title proper = Parallel title : other title information
For this title, that’s:
Massenet & his letters = Massenet en toutes lettres : a new biography