Originally Posted by
flyingfkb
That is correct but it can cause some hick-ups. Example: A person with dual-citizienship, German and US, enters Germany on his/her US passport. He/She will get a stamp to stay for 90 days. He/She now leaves Germany one day on his/her German passport and never collects the exit stamp. The next he/she enters Germany again on his/her US passport and the border agent sees that the exit stamp from the last stay is missing. Now the questioning is starting. For this reason it is advisable always to use the correct passport.
Of course, this is what I was referring to in
#35 . My point is simply that there is no explicit requirement to for a EU-country citizen enter the EU with his EU-country passport. Nevertheless, for the very small percentage of people this applies to (dual and triple citizens, for example) it makes sense to do so.