Reference field lookup value is not populating correctly, it open up the selected record.
For Example, open new incident window (incident.do). Try to add value on assigned to field using lookup list and select any user:
It open up the user record in Reference List view:
Duplicate reference fields present on the form
The field that has the issue, make sure its not duplicate on the form in ay section.
Here is an example, duplicate Assigned to field present on incident form:
This is not a problem as we should not have duplicate fields on the form, having duplicate fields can cause other issues also