Mayadigger's looks like a true Celtic
La Tene fibula
. The foot ends in a bird-head form typical of Continental Celts
To me Okidoki
's looks like it is a Thraco-Getic type
, same dating but not different culture. It would originate in Romania
or northern Bulgaria
. Are you sure it is a Dutch find? There are several dealers in the Netherlands who import most of their stuff from eastern Europe.