Complex sentence: In 1897-98, East Croydon and New Croydon were merged into a single station with three island platforms, which remain today, but the two stations kept separate booking accounts until 1924.
Split into simpler sentences: In 1897-98, East Croydon and New Croydon stations were merged into a single station equipped with three island platforms, which remain today. Even so, the two stations kept separate booking accounts until 1924.