John Flynn Sr., John R. Flynn Jr. and Leona Flynn, who finished building the Georgian-style duplex in 2015, sold the townhouse at 180 Sunset Avenue to a Palm Beach couple.
The Flynns sold the other townhouse, at 176 Sunset Avenue, last May for $5.9 million to an affiliate of Franklin Templeton Investments, headed by billionaire and Palm Beach resident Charles Johnson.
The Flynn family has a private, Dublin-based development company with a portfolio of projects in Ireland and England.
Judith and Thomas Iovino, who bought the townhouse at 180 Sunset Avenue, just listed their nearby townhouse at 152 Sunset Avenue for sale for $5.3 million.