Message type & has already been defined in model view &

What causes this issue?

In connection with a sender and receiver a message type can only be
defined in several model views if the periods of validity of the model
views are disjunctive.
The message type &V1& for sender &V3& and receiver &V4& is already
defined in the model view &V2&, whose period of validity coincides with
that of the model view to be updated.

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?

Error message extract from SAP system. Copyright SAP SE.