Theoretically yes, standard should be no different from what manufacturers claim, the reality is though that there will always be some variation. Some cars may produce slightly better or worse power than others for example, dependent upon maintenance regime, how it was run in and how tight the engine is (if its new), mileage, fuel used, even ECU parameters (where ECUs adapt to 'learn' a particular driving style or usage profile for example). Some cars will generally make more or less than the manufacter claims.
Standard B7 Audi RS4s almost never make the 414bhp claimed, E46 M3s rarely make 343ps/bhp as discussed...then you have cars like the Mk5/6 Golf GTI that generally always dyno at more than the power claimed by VW as 'standard'.
Having it dyno'd lets you know its healthy and allows a more accurate 'before and after' comparison....whether you feel its worth the bother to dyno a stock car is of course up to you, but at least you should have a clearer picture of how much extra power any remap/mods would give you.