GarageBand audio duplicating and repeating after recording is stopped

Create new track (opt/cmd/N), record - audio track appears normal as it records, hit spacebar to stop and audio file duplicates itself after the play head. This is a new problem on previously fully functioning project. I can still record but have to select/delete the duplicate files after. Have uninstalled and re-installed GB a few times but this has not resolved the problem. Can anyone help? Thanks. Martin