I tired once to add a 2nd extruder to my printer. but I found that levelling was a pain. even with two identical extruders. the hotends would be slightly different lengths. and it was difficult to adjust them to be the same. Perhaps less of an issue with a printer that has this preset but as a DIY option it can be a pain.. BTW once i did get it working. never used it and removed the 2nd head a month later.