Rashi: I am not settled with this Perush. (Do'eg surely feared lest David kill him for inciting Sha'ul to try to kill David, and for killing Kohanei Nov. Perhaps he hoped to appease him by bringing Sha'ul's crown to him, and saying that he killed Sha'ul. However, Do'eg is called ha'Edomi, and this man was Amaleki. Further, David recognized Do'eg (1:22:22), yet here (verse 8) he asked "who are you?"! Did he not recognize him due to the earth on his head?! - PF)