Exact data match hash comparison

Hello Everyone,

Please check if this scenario is possible in Exact data match.

I have uploaded 3000 rows on week 1, that successfully got hashed and uploaded to the EDM datastore. During week 2, if I upload only 500 rows it should not upload it as number of rows have come down drastically. Have anybody experienced this scenario? any suggestions or advise on this front is much appreciated. Thanks