Given to the first-born of twins. Acholi naming strongly marks birth order and the circumstances of birth, and twin births carry their own dedicated set of names.
Source: Acholi twin-naming convention, cross-referenced across Wikipedia (Okello), an academic paper on Acholi twin rituals (academia.edu), and independent Acholi-culture writeups (whereonplanetearth.com, socialpromiseblog.wordpress.com)