Both, neither, and either retain the dual form, which is super weird.
Both, neither, either 保留双重形式，超级奇怪。
英语百科
Dual (grammatical number)
Dual (abbreviated DU) is a grammatical number that some languages use in addition to singular and plural. When a noun or pronoun appears in dual form, it is interpreted as referring to precisely two of the entities (objects or persons) identified by the noun or pronoun. Verbs can also have dual agreement forms in these languages.