a question about e&g wide fender flares

[SOFTTAILJC]

i want a set of e&g wide flares,but in their instruction manuel installing them has me asking this question.... why the hell do you take off factory flares,, remasking tape them back on..then lineup new wide flares over them and screw them in place???? do the factory flares stay on under the new flares or do you had to remove the newly installed flares and take off the old just to install new ones again??? the instructions do not explain this at all and i seem to be missing something here ... i just don't get it, maybe its me....i down loaded the instruction manuel and went over it a hundred times but i just don't get it.....i think rodster and phil have done the install...i need answers fast,,, its driving me nuts......thanks .....soft...