I suppose it depends on how large the respective exhibit will be, and what specific duiker you want to display. Personally, I’ve found that mixing Yellow-Backed Duikers with Bongos seems to work well, and that mixing the latter with primates have worked in some places before. Really, the most problematic animal would be the Red River Hogs; but even they could feasibly work if you are willing to take the risks that they bring.