Duplicate records in relationship tables

HI ALL,

We are facing duplicate entries issue in report, as per report record are duplicate but if you search the same in Account module list view, then there is only one entry

And after debugging we found that we have relationship between Accounts and custom module and duplicate entries are there in relationship table hence, it show duplicate entries in report also.
Can anyone let us know what is the root cause for the same.
Also please suggest on how to find such entries clear it.

Relationship is : 1 custom module to Many Accounts.

Kindest Regards,

Shreya