Apikorsim in Shulhan Arukh

Yesterday, while in Halakhah (Jewish law) seder (time set aside for learning texts), learning the Shulhan Arukh, chapter 53, when I came across the following that Rabbi Karo wrote in section 18:

האומר: 'איני יורד לפני התיבה מפני שהגדי צבועין או מפני שברגלי סנדל,' לא ירד באותה תפלה כלל, מפני שדרך האפיקורסין להקפיד בכך, וחיישינן שמא אפיקורסות נזרקת בו

What was interesting was that there was an interesting description of apikorsim (Hebraicization of Epicurus/Epicurean) here. However, I was struck by an apikorus being mentioned in a Jewish legal code as peculiar(!). I then ran a Bar-Ilan search on this term and found that this is the only time it pops up in the Shulhan Arukh. Moreover, this הלכה comes up from מגילה כד, עמוד ב, where the language there is מינים. This latter term is different from the term above, as the latter refers to some sort of Judeo-Christians, or Christians, per se (though I am rather on the naive side as to this term, however), while the former is not.
I wonder if maybe there were manuscript variations, but, more likely, Rabbi Karo probably wasn't concerned with the distinction between these two different groups, and accidently inserted this term in lieu of the terminology of חז"ל.
(I apologize for the use of Hebrew in this posting without translating, and I know people request that I translate, but I'm not sure how interested people will be in this posting who are not tremendously involved in these matters, and it's kind of abstruse.)