Up to 20 people — or nearly three times the official count — may have died in the city’s latest Legionnaires outbreak because of misdiagnoses, according to the lawyer for four fatal victims who filed notices of claims over the mess Tuesday. 7 Lawyer Ben Crump (left) and the Rev Al Sharpton on Tuesday said deaths from the recent Harlem Legionnaires’ outbreak are likely vastly undercounted. Scott’s father Bruce Scott, 53, passed away from Legionnaires’ disease. Gloria Cooley said her mom, June, suffered for two weeks in a hospital room before doctors agreed to test for Legionnaires. Sharpton also called on the mayoral candidates to take the issue seriously and to make it part of their campaign.