Those are all good (assuming you meant 1,4 for the last one). What about the isomers without a bromine at the 1 position?
Sorry mistyped some of them. so it is 1,1-dibromobutane, 1,2-dibromobutane, 1,3-dibromobutane and 1,4dibromobutane , 2,2-dibromobutane and 2,3-dibromobutane???
Sorry mistyped some of them. so it is 1,1-dibromobutane, 1,2-dibromobutane, 1,3-dibromobutane and 1,4dibromobutane , 2,2-dibromobutane and 2,3-dibromobutane???