Let (X1,Y1),...,(Xm,Ym ) be m independent identicallydistributed bivariate vectorsandL1 = β1X1 + ... + βmXm , L2 = β1X1 + ... + βmXm are two linear forms with positive coefficients.We study two problems:under what conditions does the equidistribution of L 1 and L 2imply the same property forX 1 and Y 1, and under what conditions does the independence of L 1and L 2 entail independenceof X 1 and Y 1?Some analytical sufficient conditions are obtained and it is shownthat in general they can not be weakened.