Why is a previous absence deleted when assigne a new an absence?

Duplicity of absences

Cause

The user or manager try to assign two absences per hours on the same day. 

Solution

It is not currently possible to assign two absences per hour on the same day. For this reason, if two absences are added, the first one will be replaced by the last one. To reduce the user's working day you can edit the user's working day for that day.