I did ask from the consular at the Finnish consulate in LA but they didn't seem to have the answer whether you can have two passports. I do agree with you that the stamps shouldn't make any difference because you can have a "fresh" passport as often as you want.

I have never had a problem with the US immigration (gone through 40+ times) but got interviewed by three Israelis when entering TLV first time. They really couldn't believe why anybody would come there during the "war". I just told them that I hadn't seen any missiles hitting TLV on CNN and that I heard that the GAY nightlife is great there.

My hunch is that they finally believed that I am not a "threat" to the Israeli society and let me in.