Just to follow up. The Dutch to Dutch dictionary (Hedendaags Nederlands) is DRM-protected, but differently than other DRM protected books licensed to the Kindle's serial number. I can't seem to undo it but it seems there's no need for it either. The two other dictionaries (NL to EN and EN to NL) are MOBI formatted and don't seem to be DRM protected.
I have copied all three dictionaries with Calibre to my wife's Paperwhite I and all three work like a charm. She is using the same Amazon account so maybe that's the reason they work, but maybe not. At least I don't have to replace her Kindle too.
Anyhow, happy Easter!
