  In recent years, the emergence of DNA storage systems has led to a widespread
focus on the research of codes correcting insertions, deletions, and classic
substitutions. During the initial investigation, Levenshtein discovered the VT
codes are precisely capable of correcting single insertion/deletion and then
extended the VT construction to single-insertion/deletion/substitution
($1$-ins/del/sub) correcting codes. Inspired by this, we generalize the recent
findings of $1$-del $1$-sub correcting codes with redundancy $6\log_{2}n+O(1)$
to more general $2$-ins/del/sub correcting codes without increasing the
redundancy. Our key technique is to apply higher-order VT syndromes to distinct
objects and accomplish a systematic classification of all error patterns.
