If I set the question attribute "Use dropdown" for a dual scale question type the options are displayed in radio buttons ==> too me this settings works the other way round as it should be ==> but perhaps just the naming at the question settings isn't correct.

Although: The official LimeSurvey sample survey both question types "Array (Flexible Labels) dual scale (radio)" and "Array (Flexible Labels) dual scale (dropdown)" have set the same parameter at question attribute "Use dropdown" ==> they get displayed the same way ==> after fixing this bug one of them has to be adjusted!