Comment by Tade0
Strange that this exists. Polish also has dz(it's the same phoneme), along with dź, dż, sz, cz, all of which use Title case in, among other instances, acronyms (e.g. RiGCz), but I'm not aware of any special code points for them - dz is definitely always spelled as d-z.
Does Polish treat them as distinct letters in their own right for sorting purposes? That is usually when you see digraphs appear in (at least some) national encodings, from whence they end up in Unicode for compatibility reasons.