The box is still abnormally huge for a typical driver of the size -- i.e. two drivers in a shared 14 cu. ft. enclosure is theoretically the same as two drivers, each in their separate 7 cu. ft. enclosure. If the port lengths/sizes are different for each woofer enclosure, and/or the volume of each enclosure is substantially different, then the woofers/enclosures are tuned differently. But from your description of this as a "stereo" sub, that's probably not the case, and your stuffing difference is probably arbitrary.
I would recommend that you figure out the exact model of the drivers in your box, and download a software speaker-box simulator like WinISD. You can then use the software to get an idea about the effect of the size/tuning of the box versus the driver, and how they interact . . . WinISD Pro also has some rudimentary tools for predicting maximum cone excursion and stuffing losses, so you can study these effects by means other than simply trial and error.
Once you're familiar with some of the lanugage and parameters, you can then approach the designer to figure out whether or not he was smoking something when he built it . . . and maybe exactly what he was thinking.
I would recommend that you figure out the exact model of the drivers in your box, and download a software speaker-box simulator like WinISD. You can then use the software to get an idea about the effect of the size/tuning of the box versus the driver, and how they interact . . . WinISD Pro also has some rudimentary tools for predicting maximum cone excursion and stuffing losses, so you can study these effects by means other than simply trial and error.
Once you're familiar with some of the lanugage and parameters, you can then approach the designer to figure out whether or not he was smoking something when he built it . . . and maybe exactly what he was thinking.