Lightroom - won't import 'Duplicates'

Hi, 

I have scanned a lot of old images and am importing them into Lightroom (not Classic) in batches but it identified the images as duplicates sometimes (they are not as I have looked through the files) there seems to be no way of diabling this function that I can see...can you help ? It is possible that the imges may have duplicate numbering. Can anyone help ?Thanks