The ALA will load duplicate records unless they are filtered out by the source of the data and not provided.  The ALA does run a regular duplicate detection process that picks up similar records based on location information such as coordinates, the date of the sighting, who made the sighting and a other identifier fields.  Similar records are flagged as "associated records" and one is selected as the "representative record" based on the most complete record.  You can view and filter on this information in the "Associated record type" facet.