Oliver started to spell the name Antipas as Antipah in 𝓞, but then he immediately erased the partially written h and overwrote it with an s. The name occurs two more times in the text (in the following verses 9 and 10). There we see evidence of Oliver Cowdery writing Antipas as Antipus, twice in 𝓞 and once in 𝓟:
The scribes tended to mix up a and u in their scribal work (see, for instance, the discussion regarding the name Cumorah under Mormon 6:2). For each name involving a potential mix-up for these vowels, we follow the earliest textual sources, thus Antipas as the name of the mount since this is the immediately corrected spelling for the name in 𝓞 the first time the name appears in the text.
Notice that there is a military leader later on in the book of Alma whose name is spelled Antipus, according to the earliest textual sources in 𝓞. For the spelling of that name, see the discussion under Alma 56:18. These two examples show that Book of Mormon names can minimally differ from one another, just like Oneidah, Onidah, and Onihah (see the discussion just above under Alma 47:5 regarding the name Oneidah).
Summary: Accept Antipas as the name of the mount in Alma 47:7, 9–10; the earliest extant reading supports the a rather than the u vowel in the last syllable of this name.