A.T. Robertson Commentary Luke 16:13

"No servant can serve two masters: for either he will hate the one, and love the other; or else he will hold to one, and despise the other. Ye cannot serve God and mammon." — Luke 16:13 (ASV)

Servant (οικετης). Household (οικος) servant. This is the only addition to Mt 6:24 where otherwise the language is precisely the same, which see. Either Matthew or Luke has put the λογιον in the wrong place or Jesus spoke it twice. It suits perfectly each context. There is no real reason for objecting to repetition of favourite sayings by Jesus.