If the props turn the same way (which they do on the ATR) then there will be a critical engine. Because the the thrust is further from the CofG on the right engine (with clockwise rotation), all other things being equal, you will need more rudder to keep the aircraft straight if the left engine stops.
Now as to why you would need to know this during an actual engine failure in a modern turboprop is another question. The actions for handling an engine failure are the same regardless of which engine fails.