Here in 𝓞, Oliver Cowdery wrote the u in Antipus so that it looks more like an a, giving Antipas. As noted under Alma 47:7, Antipas is actually the name of a mountain. And interestingly, that name was frequently miswritten in 𝓞 as Antipus (but not for its first occurrence, in Alma 47:7). Here in Alma 56, the name refers to a military leader, Antipus. His name is found 20 times in the text (all here in this chapter); 13 instances are fully extant in 𝓞, and all but this one in verse 18 read Antipus. The first occurrence of the name, in verse 9, is extant only for the last three letters of the name. But in the ultraviolet photos for this page of 𝓞, the vowel appears to be a u, not an a. For all 20 occurrences of the name in 𝓟, Oliver wrote it as Antipus. Here in Alma 56, the critical text will maintain the spelling Antipus for the name of the military leader, a spelling that is distinct from Antipas, the name of the mountain in Alma 47.
Summary: Maintain the name Antipus for the military leader, referred to 20 times in Alma 56.