So my custom Object is a student that stores first name, last name, grade level, school etc. When I try and import this from my csv file that has all the data it doesn't import all of them. I know why they were not imported. My field name for my standard field has to do with student's last names and people can have last names that are the same so any kids who's last names were not unique were not added in when I imported. Is there a way to get around this. Can I change how the importer determines a duplicate record?
It shouldn't be the data loader that is detecting the duplicates. There must be some other duplication detector in your org - you should check the duplication detection setup as well as any triggers or processes that might be detecting the duplicate records.