This menu doesn't have an effect on the importing while in the "Current File" asset library. This can be quite confusing. However, just hiding the menu may be a temporary solution. Decision actually to instead show a different menu, that allows choosing between duplicating and reusing data on drop. This is being reviewed here https://developer.blender.org/D12879. Meanwhile (or in case we end up rejecting that), this change should avoid some confusion. Differential Revision: https://developer.blender.org/D12752