Time inconsistency between trip &1 and attendance on &2 as of &3 in SA &4

What causes this issue?

The separation allowance event to be processed has parallel business
trips that do not agree with the presences at the duty station in the
separation allowance event.

System Response

The separation allowance event can be saved, but not approved.

How to fix this error?

Correct the general data of the business trip or the presence time span
at the duty station of the separation allowance event.
Parallel business trips must be either completely within or outside of
such a presence time frame.

Procedure for System Administrators

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

Error message extract from SAP system. Copyright SAP SE.