If deemed necessary they may ask it again as they destroy the details within 90 days. This shall avoid a match with the database and may cause unnecessary scrutiny for a clean person. I also migrated to Canada as a PR and i was asked for it again during Citizenship application process.I was asked to give RCMP fingerprints when I immigrated from within Canada. I suspect people who immigrate from other countires to Canada were not asked to submit them that time. So I am sure people like us who already gave RCMP finger prints will not be asked again them at the citizenship process as they can verify them.