The source paradigm presents nominative forms, using -āni in the dual and -ūna in the masculine plural. Syntactic case can change those endings.
Word / formMeaning / explanation
مَنْصُورَانِtwo men helped, nominative.
مَنْصُورَيْنِthe same dual in accusative/genitive.
مَنْصُورُونَmen helped, nominative.
مَنْصُورِينَthe same plural in accusative/genitive.
The gender and number do not change; syntax alters the case ending. These case endings do not convert a passive participle into an active one.