Entry in partner table already exists

What causes this issue?

An entry with the following key already exists in table EDPP1:
&v1&
This relates to the key fields in table EDPP1:
PARNUM Partner number
PARTYP Partner type

System Response

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

How to fix this error?

Please check the EDI partner profiles.
IF &DEVICE&='SCREEN'
<ds:TRAN.WE20>Execute function</>
ENDIF

Error message extract from SAP system. Copyright SAP SE.