Complex sentence: Lanfranco is known for keenly competing against fellow Carracci trainee, Domenichino and ultimately accusing him of plagiarism for his painting of the "Confession of St. Jerome", now in the Vatican.
Split into simpler sentences: Lanfranco is known for keenly competing against fellow Carracci trainee, Domenichino. Lanfranco ultimately accused Domenichino of plagiarism for his painting of the "Confession of St. Jerome", now in the Vatican.