Sort data by date and exclude duplicate data

Hi,

I am using a DirectQuery connection to and SQL data base that has data uploaded from clients on a montly basis.

I need to exclude data that has been uploaded in duplicate for the same time period.

I feel I need to sort by month, then remove the duplicate data in that time period but I am not sure how to do this.

Should I use a dax expression?  The problem being if I create a new Column I am unsure how this will effect my relational data.

The data is comprised of over 100 different tables that are all related, half of them  directly back to the table I need to filter.

I can not include a screen shot as it is sensitive data.

Thanks in advance