The paralleling of the two lines of kings also furnishes the key to the explanation of how the different names and a different setting for the Hroar-Helgi story, from those found in other versions, got into Saxo's version. Since the Hroar-Helgi story appears in the same place in his line of kings as in that of the _Skjọldungasaga_, he must also have known the names that really belonged to the story. But he had told the story about Halfdan, Hroar, Helgi, and Hrolf Kraki (in its second stage of development, see p. 66) once before, and therefore could not consistently tell a different story about the same men. The story was, however, in existence and was too good to be discarded, so he retained it, but disguised it by making arbitrary changes. This explains the loss, which otherwise would be very strange, of such well known names as Hroar, Helgi, and Hrolf Kraki. The only incentive any one could have to change the names would be just that which Saxo had, namely that he had used them before in another connection. He retained the name Frothi, which appears so often in the Danish line of kings that its reappearance would cause no difficulty; and his retention of Frothi as the slayer of his brother is additional evidence that to him, not to Ingjald, was this unenviable rôle first assigned. Ingjald, whom he has in his story about Hrolf Kraki, he also retained, but in a different relationship from that in his second book. It will be observed that Saxo merely shifted the name Halfdan from father to son, and that Harald, almost a conventional name, he employed twice. Finally, he introduced a strange person, Olaf, about whom, he says, nothing, practically, was known. But since Saxo has the Hroar-Helgi story substantially as it is in the _Hrólfssaga_, except for the changed names, the author of the _Skjọldungasaga_, or its source, whose version of the story occurs in the same place in the line of Danish kings as Saxo's, must also have known the story in the same version. This we shall find was actually the case, and that the story as it appears in the _Skjọldungasaga_ is an attempt at reconciling conflicting elements in ancient tradition. As already stated, according to the _Grottasọngr_ (from about 950), Frothi is the brother of Halfdan and slays him. But according to an equally old tradition, the story on which the Ingjald lay in Saxo's sixth book is based, Frothi is Ingjald's father and is himself slain. The events that gave rise to this lay are also narrated in Saxo's sixth book and are as follows.