DMX effects are generally not designed to overlap.  Adding a "Red Par Light" effect and a "Blue Par Light" effect over a simultaneous time range might result in purple light for LED fixtures, but that's not a guarantee.  The effect libraries are generally designed with the expectation that if you want a purple light, you'd add a "Purple Par Light" effect -- no overlapping required. There are two main exceptions: 1) modifier effects like "With Strobing" or "With Safety Channel", and 2) multi-head fixtures for which a per-head effect like "Head 2 Standard Flame" sometimes can apply in parallel with other per-head effects like "Head 3 Standard Flame", depending on the fixture. The function "DMX > Detect and fix overlapping effects" helps identify and fix overlapping effects that shouldn't overlap.  It is an important function, because improperly overlapping effects might appear one way in the simulation and another way in real life.  The function is available in the menu item of Figure 1.   Figure 1 – It is a good idea to use this function for DMX shows to ensure the simulation represents what you will see in real life.   If you choose "Fix" in the dialog of "DMX > Detect and fix overlapping effects" shown in Figure 2, the function will truncate DMX effects that overlap later effects on the same fixture by shortening the durations of the earlier effects to make them line up back to back with the later effects.  DMX effects of type "sfx" and "light" have adjustable duration, so shortening their durations is not a problem.  DMX effects of type "flame" have non-adjustable durations, though, so in order to change their durations, the function also needs to change their type to "sfx". Changing the type to "sfx" is nothing to be afraid of.  Flame effects could have type "flame" or "sfx" without much difference.   The list of differences is in: Why is ‘Type’ so important? What depends on it?.  The reason flames generally have type "flame" is that designers tend to think about flame effects as having a specific duration, similar to pyro, in contrast with DMX light flashes whose durations are more fluid.  The non-adjustable durations of type "flame" enforce that expectation and avoid the possibility of ending up with a "Long Flame" effect whose duration is actually short.   Figure 2 – The function may need to change the type of "flame" effects to "sfx" in order to adjust their duration.   Exemptions As mentioned above, modifier effects like "With Safety Channel" effects, and multi-head fixture effects may legitimately overlap.  They are exempted from this function.  The specific list of exemptions is: Effect ID is 0000 (safety channel) or 1201 (initialize fixture). Effect description contains the subphrase "AFETY" or "afety". The fixture definition contains the attribute "supportsOverlappingEvents", with value = TRUE.  This field corresponds to the checkbox "Fixture has multiple heads" on the "Create DMX effect..." dialog. Effect VDL is blank. Effect VDL contains the subphrase "odifier". Aside from these exemptions, the function will detect and fix all overlapping DMX effects.