A witness who testifies as a lay witness offering either factual testimony and/or lay opinion testimony and also testifies as an expert offering expert opinion testimony provides what is know n as "dual role testimony." The question pr esented is:

Must a district court exercising its "gatekeeping role" unde r Rule 702 of the Federal Rules of Evidence in som e instances exclude dual role testimony unde r Rule 702 a s not helpful to the trier of fact and/or unde r Rule 403 a s evidence whose probative value is out weighed by its prejudicial effect in misleading and confusing the jury?

Must a district court exercising its 'gatekeeping role' under Rule 702 of the Federal Rules of Evidence in some instances exclude dual role testimony under Rule 702 as not helpful to the trier of fact and/or under Rule 403 as evidence whose probative value is outweighed by its prejudicial effect in misleading and confusing the jury?