Mync has two search mode for duplicate clips as following

Search for exact match

If highly suspected duplicate files are found, they will be inspected are both completely identical. Although it will take time for checking the entire data, the result is reliable if the files are determined to be identical.

Library search

Search is proceeded within the Mync database to find clips that matches specified item ([File Name], [Size], or [Modified date time]). You need to check if they are duplicate files or not based on the search result.