For contract &1 move-out document &2 already entered

What causes this issue?

While creating a move-out document, you have used a contract for which
a move-out document already exists.

System Response

It is not possible to create a second move-out document for the
contract.

How to fix this error?

See the table of contracts for which a move-out document needs to be
created.

Error message extract from SAP system. Copyright SAP SE.