Shoham (onyx) and Ibri (Hebrew) do not occur as individual names elsewhere, but there is no reason to doubt their genuineness.
Some commentators pronounce 1 Chronicles 24:26-27, spurious, against the evidence of the ancient versions.
Related Commentaries of 1 Chronicles 24:27
1 Chronicles 24:27
27 The sons of Merari by Jaaziah; Beno, and Shoham, and Zaccur, and Ibri.