Tosafos writes that the possibility of a "me'ukav gett shichrur" eating Teruma (that the gemara has a discussion about) is speaking of a half eved half ben chorin. The maharshal points out that this is not possible, because a half ben chorin should not be able to eat teruma since his half ben chorin side is definitely assur from eating Teruma. The Maharsha disagrees with the Maharsha (kidarko bakodesh) by proving that just as a chatzi ben chorin cannot be mekadesh an isha and his kiddushin is not binding at all, even though his ben chorin side should technically be permitted to a regular bas yisroel, so too it is possible that if he is a chatzi eved of a kohen he can eat teruma without worrying about his chatzi ben chorin side. The Karnei Ri'eim and Pnei Yehoshua point out that kiddushin is completely different than Teruma. The rationale for kiddushin not to be binding at all is that he it can only be binding on half of him, and there is no such thing as kiddushin of half of a person. But in regard to Teruma, it should certainly be assur to eat Teruma since his chatzi ben chorin side is not owned by a kohen. Although the Pnei Yehoshua doesn't agree with the comparison to kiddushin, he attempts to justify the position of the Maharsha and Tosafos that a chatzi eved chatzi ben chorin, may qualify as a kinyan kaspo even on the side of the ben chorin, since practically speaking he is a person who is at least somewhat owned by a master. The status of kinyan kaspo would enable him to eat Teruma. However, the Pnei Yehoshua rejects this suggestion based on a Toras Kohanim that an eved owned in partnership of a kohen and a zar, cannot eat teruma.