Personnel number &2 is assigned several times in client &1

What causes this issue?

In client &V1&, more than one user was assigned to the personnel number
&V2& in the view <LS>Assignment: User - Personnel Number</> (V_T513A)
It is, however, only possible to assign one user to a personnel number.

System Response

The relevant table entries are not converted.

How to fix this error?

Maintain the correct entries in the <LS>Communication</> infotype
(0105).

Error message extract from SAP system. Copyright SAP SE.