I have the same problem!
Repeated values appearing only once by displaytype ‘combobox’. By displaytypes ‘typahead’ and ‘text field’ are all repeating values of the table in the valuelist.
For who is interested , I isolated the problem in a micro-application, and added it attached.
The screenshot is showing the repeated values, an fields with the “Display Type” Text Field (yellow) and Type Ahead (red) the Display Type “Combobox” (geen) is working fine.