Русско-английский словарь пословиц и поговорок
ДВА ВОРА ДЕРУТСЯ ЧЕСТНОМУ ПОЛЬЗА
When the dishonest quarrel or fight, honest men gain by it
Cf:The death of the wolves is the safety of the sheep (Br.). When knaves (rogues) fall out, honest men come by their own (Am.,Br.). When thieves fall out, honest men come by their own (Br.). When thieves fall out, honest men get their due (Am.)