How to detect Duplicate records in custom Entity

HI All, 

I  have 2 custom entity Inquiry and Sample orders in CRM 9.2 and they both are mapped.  There is some issue due to which duplicate records are creating.

First Inquiry Record is get created. Once Inq is approved then workflow will create Sample order Record

Inquiry                       Sample

InquiryNo.                 SamplorderNo.

Now in Sample Order View it showing like this

Inquiry No    SampleOrderNo            CompnayName           ShippingAddress                            Product

Inq-001        SMPL-001                               A                       ShipAddr1                                       P1
Inq-001        SMPL-002                               A                       ShipAddr1                                       P1
Inq-001        SMPL-003                              A                       ShipAddr1                                       P1
Inq-001        SMPL-004                               A                       ShipAddr1                                       P1

My Query is like - How I can find all such duplicate records ?

                             Can we set 1:1 relation ship between these Entities so that such duplicate record will create ?
                               Sample Order No and Inquiry is getting generated by a plugin  should we check any thing there
                            

                           Any other suggestion to avoid creating of duplicate  any expert thought.