If you find that issuing a scene twice (particularly a scene with low levels) causes the levels to jump at the DMX level,

 then you need to check that you are not targeting the DMX channels twice.  You can set the following options to ensure this:

 SO7;1:        [Scenes only target the Analogue Output]

 SO3;2:        [DMX channels follow the Analogue Outputs]

 Now scenes can be issued many times with the expected behaviour

 Andy