I've seen a helicopter fly with one blade and a counter balance in place of the other. Yes, they both weighed the same but as one was a full length blade and the counterweight about 6" as I recall, the CGs were obviously much different.

Also I believe it is common in some racing airplanes to fly with one bladed props with a counterweight. Using only one blade reduces drag.

With that said I have never tried it myself. I always match the CGs of the blades when I balance them.