Robert Allen, a key witness in the homicide litigation of XXXTENTACION, is now slated to testify in YNW Melly’s double-murder retrial. According to court documents released on Oct. 10, he is among seven new witnesses the Florida state attorney plans to introduce. Allen played a crucial role in the 2018 XXXTENTACION case, where he testified against co-defendants Michael Boatwright, Dedrick …