There are more words but they are from Tolkien's earlier conceptional periods. Tolkien likely changed these words as he evolved the aesthetics and completeness of the languages. You may even find languages that Tolkien later rejected. Do not mix words from different time periods unless you are familiar with the phonetic developments.
matwa
whether, which of two
matwa e·antane sine nyén atwa tyén
did he give this to mé or to yóu?
matwe
pronoun. whether, which of two
An pronominal correlative meaning “whether, which of two” appearing in Demonstrative, Relative, and Correlative Stems (DRC) from 1948 (PE23/107), a combination of interrogative ᴹQ. ma and ᴹQ. atwe “one of two”.
Below: Tolkien's Late Period (1950–1973). These are from Tolkien's late conceptual period — his most settled forms of the languages. Prefer these over the earlier ones above when composing new text.
An adjectival correlative meaning “whether, which of two” appearing in Demonstrative, Relative, and Correlative Stems (DRC) from 1948 (PE23/107), a combination of interrogative ᴹQ. ma and ᴹQ. atwa “either”. Presumably like atta “two”, the noun modified by matwa remains in the singular, such as: matwa nér i elda cenne “which (of two) men did the Elf see”. It can can also be used (instead of ma) to introduce any question where there are only two possible answers. In such cases atwa “either” is used separate the alternatives: matwa i elda lende formen atwa hyarmen “did the Elf travel north or south”.