use re 'multi_captures';

":aa2bb4cc6dd8" =~ / (:)
                     (?: (\w\w) (\d) )* /x;

dd $&;  #-> ":aa2bb4cc6dd8"
dd $1;  #-> ":"
dd $2;  #-> ["aa", "bb", "cc", "dd"]
dd $3;  #-> [2, 4, 6, 8]