Hi Allen,
By examining the screenshot you attached, we suspect that the dropdown you render on the left is not a Syncfusion one whereas the one on the center is ej2-dropdownlist. Moreover, we would like to know you that usage of tag helper e-dropdownlist-fields once is enough for each dropdownlist. If we misunderstood your query, kindly revert the exact scenario of where you are encountering the issue and code snippet of dropdownlist rendering. If possible provide video which demonstrates your issue.
Regards,
Jeyanth.