ḥr(“Horus”) + ꜣḫtj(“of the Akhet”). Later, in the New Kingdom, ꜣḫtj was reinterpreted as the dual of ꜣḫt(“Akhet”) instead of a nisba adjective derived from it, rendering a new interpretation of ḥr-ꜣḫtj as a direct genitive construction meaning ‘Horus of the Two Akhets’.
“Ḥr.w-ꜣḫ.tj (lemma ID 107800)”, in Thesaurus Linguae Aegyptiae[1], Corpus issue 18, Web app version 2.1.5, Tonio Sebastian Richter & Daniel A. Werning by order of the Berlin-Brandenburgische Akademie der Wissenschaften and Hans-Werner Fischer-Elfert & Peter Dils by order of the Sächsische Akademie der Wissenschaften zu Leipzig, 2004–26 July 2023
James P[eter] Allen (2010) Middle Egyptian: An Introduction to the Language and Culture of Hieroglyphs, 2nd edition, Cambridge: Cambridge University Press, →ISBN, page 149.