See also: Gore in Pictorial Dictionary of Heraldry.
Use of both a gore and a gore sinister, or use of a charged gore, would be considered a step from period practice (SFPP).
Gore (1) §
Gore (2) §
Source: Wappen besonders von deutschen Geschlechtern. Artist unknown. (Folio 40v.)
Gore (3) §
Gore Sinister §
Two Gores §