yes it was, it was one tradition in Greece. And the Crown Prince of Kings Constantine- sofia was George as his grandfather the King George. Princess Irene was born in wartime, it was customary to put the name of Irene, because it means peace.
Constantine I of Greece was named after his mother's father, the Grand Duke Constantine of Russia. It was also a name of great significance for the Greeks and those patriots who had espoused the Megali Idea of a united Greek people led from Constantinople.