I like this method:
Create table dst with the same structure, but add the digital field DupCount
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do request:
INSERT INTO dst SELECT * FROM src ON DUPLICATE KEY UPDATE dst.DupCount = dst.DupCount +1
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DupCount for each row will contain the number of repeats encountered.
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You can write a script that will create table dst, copy, thus there is data, delete the original table and rename dst to src.