Trigger has serious flaw - ALG Defense ACT Advanced Combat Trigger for AR-15/AR-10

Bought this trigger for a premium build. Installed it and performed several function tests including "hammer fall" test. Worked great and had a clean, crisp break with almost no take up. Took it to the range and about the ninth shot I experienced a double fire. This continued sporadically through about 200 rounds. When I got home I removed the lower (a Colt) and performed more funtion tests. Sure enough, about the fifth time the hammer fell when the trigger was released. This is repeatable. This is my fifth trigger installation - the first with any problem.