Doesn't that almost describe this particular speaker even when used as intended?
That happens with ANY loudspeaker(s) that have drivers arriving at the listeners ears at more than 1/4 wavelength apart in time.
That is why it is important to use a single source of sound, or if you use multiple cabinets, use cabinets that have large enough mouths so that they have real pattern control so the levels from the different cabinets are very different, so they don't interfere with each other.
Small horns-or narrow horns that are not LARGE, simple do NOT provide this needed pattern control