Orchos Tzadikim and Rambam

In his commentary to Avos 1:17, the Rambam discusses the middah of Shetika. He says ???? ???? ????? and then proceeds to discuss a maaseh which explains the four categories of Shetika. Barring a few word changes, this is exactly what the Orchos Tzadikim says in Shaar Hashetika, and the real name of the Orchos Tzadikim is Sefer Hamiddos. So at first glance it would seem that the Rambam is quoting the Orchos Tzadikim. The problem with that is that although we don’t know who wrote the Orchos Tzadikim, we do know that the Orchos Tzadikim quotes the Rambam several times and especially in Shaar Hatorah he discusses seforim after the Rambam. Presumably then the Rambam is quoting a different Sefer Hamiddos (or even a sefer on middos as opposed to Sefer Hamiddos) which says what the Orchos Tzadikim says and probably the Orchos Tzadikim is actually quoting the Rambam (as you can notice many things in the Orchos Tzadikim seem to be taken straight from the Rambam even when it’s not attributed) or this other sefer that the Rambam was quoting. The thing is though that this other sefer doesn’t seem to be extant and interestingly, in the Pirkei Avos with the Peirush Harishonim, when the Rambam says ???? ???? ????? the printer in parentheses put in “????? ?????? ??? ??????”. The whole thing just seems a bit odd to me.