BILLERICA-Residents should be well aware at this point in the campaign: These candidates agree on a lot. Rep. Sean Garballey, Cindy Friedman, and Mary Ann Stewart are all progressive Democratic candidates – which showed yet again on Tuesday, a week from the primary. While the candidates for the 4th Middlesex District state Senate seat agreed on a majority of issues, they did break on a few topics during the Sun-sponsored debate at the Billerica Senior Center.