Filed from 2 published puzzles

FMINOR

Set to 2 different clues across 2 published puzzles, most often “Key of Chopin's Piano Concerto No. 2” — The New York Times, Sunday, 14 December 2003.

6 letters

Every clue on record, most used first

Key of Chopin's Piano Concerto No. 2once
The New York Times — Sunday, 14 December 2003
Key of Chopin's "Piano Concerto No. 2"once
The New York Times — Monday, 25 October 1999