No, Matty B does not have a twin brother, but he does have 2 brothers and a sister, one of which he looks quite alike. here is a photo of the brother and Matty b that look alike. this is when Matty is 8 and his brother is 9.
Matty Beadles, is "MattyB" on YouTube. He is a young rapper (aged 7 or 8). His older brother is Christian Beadles (best friend of Justin Bieber) and his sister is Caitlin Beadles (Justin Bieber's old girlfriend).