In δουλιχόδειρος (Il.2.460 and 15.692 and quotations etc. thereof), the -ου- is artificial (consider all the Homeric compound adjectives in δολιχο-; there was never a /w/ to necessitate any lengthening), but the -ει- is the regular outcome of compensatory lengthening in Ionic (cf. Attic δέρη, Aeolic δέρᾱ, Arcadian δεϝρά̄ (BCH 39 (1915) 53-97 = Schwyzer 664 = IPArk. 14, lines 14, 15, 18, 24: Orchomenos), Ionic δειρή).
Cf. δουλιχόεις in Anth.6.4 (neut.pl., by Leonidas). LSJ labels both forms 'Ion.', which is untrue for the second adjective and only half-true for the first.