Who noticed that Mr. Hyde and dr jekylls hand writing was similar?

In "Strange Case of Dr Jekyll and Mr Hyde" by Robert Louis Stevenson, it is Mr. Utterson, Jekyll's lawyer and friend, who notices the similarity in handwriting between Dr. Jekyll and Mr. Hyde. This observation becomes a crucial clue in unraveling the mysterious connection between the two characters. Utterson's discovery deepens the intrigue surrounding Jekyll's dual identity.