I think I have seen MT-32 on a couple of games ive played through SCUMM - point and click games from memory.Munt is a MT-32 emulator. MUNT emulates the MT-32 hardware utilising the original roms from an original MT-32 unit. Its not GM and is more suited to older games (Luscasarts and Sierra were big on MT-32 sound). For Duke 3D your better off sticking with a GM Soundfont.
I wouldn't class a soundfont as emulation. Its more of an approximation of what an original device sounds like.
Roland do have a Sound Canvas emulator (Sound Canvas VA) which is a VSTI plugin which I've read sounds very close to the SC Family. I'm sure its possible to get it work with DOSBOX
Thanks. Am i being blind, I dont see a download link to Sound Canvas VA. The soundfonts i linked too there are some which are based off the Sound Cancas VA.