HP Sassoon(1) 208.7 :דאי לבסוף מישתכ̇חא̇ פיגמתא לא תיפסול אילא "אחרונה‏ : so that if at the end (of the slaughtering) a defect is found, only the last one would be declared unfit
See the entire entry for pgmh n.f. defect