my co-worker is a dual ROC and USA citizen, with passports from both.
when she arrives/departs Taiwan, she always have both passports stamped
with ROC entry/exit stamps. The passport checkers always seem happy to
do it. In fact, she told me most dual ROC/USA citizens usually have both
passports stamped.
Can anyone tell me what the point is?
Thanks! 
[quote=“creamypanda”]my co-worker is a dual ROC and USA citizen, with passports from both.
when she arrives/departs Taiwan, she always have both passports stamped
with ROC entry/exit stamps. The passport checkers always seem happy to
do it. In fact, she told me most dual ROC/USA citizens usually have both
passports stamped.
Can anyone tell me what the point is?
Thanks! [/quote]
I too have this done as a matter of course as I use my Taiwan passport to enter Taiwan and my U.S. passport to return to the U.S. I do this so that when I return to the U.S., the U.S. immigration officials will see entry and exits stamps in my U.S. passport for where I have been. Otherwise, you sometimes have to go through the trouble of showing U.S. immigration both passports. It just reduces potential delays when returning to the U.S. as the immigration officials are seeing what they want to see in your U.S. passport - an entry and an exit stamp.