Yes, another one of these subs will increase the available output and will perhaps help with room problems (although it could also create room problems), but will NOT allow you to go "deeper". That's just not possible. The sub only goes so low, and doubling, tripling, or quadrupling the number you have will not "magically" make you now suddenly able to achieve a lower frequency response.
I have this sub, by the way. It has VERY substantial output capability, but I'm well-aware of it's low-end limitations. It is not known as a "bottom feeder" type "movie" subwoofer that would be desirable to achieve the Orlando "theme-park" experience that the OP speaks of. The output below 25Hz drops off quite significantly and it has no output whatsoever below 19Hz. Hence my assumption that what the OP really wants is to go "deeper" (up to an octave, even) and my comment was that simply doubling the number of subwoofers will not help toward that end at all.