AOR Reports - Issue with related records in reports showing duplicate records with same value

I’m creating report with case module.
I have one custom module relation with case.
i’m showing column from custom module in reports. and it is showing duplicate records. grop by is not working for rows.

Hey there,

Depending on the Report’s set Fields/Conditions, the report can show duplicate items if there are multiple relationships between records in the modules being reported on.
(And the Records in the Module being reported on are related to multiple records in another module)

What kind of relationship is it between your Cases and Custom Module?
(One to One / One to Many / Many to Many?)

Also, would it be possible to post a screenshot of your Fields/Conditions, to see if we can replicate/investigate?