As written...H31C−CHBrCHBr4CH3 (I had trouble representing this on the editor...the chiral carbons, 2C and 3C are not labelled but their substitution is evident).
Anyway, the beast has two chiral centres... In principle it has 2n isomers where n=2, i.e. n=the number of chiral carbons; POTENTIALLY 4 diastereomers....
Now RR is the mirror image of SS...and these are non-superposable, and I presume that only the ONE of these enantiomers is biochemically active....and the industrial synthesis would produce this isomer. But the RS disastereomer is THE SAME as the SR disastereomer.....given the symmetry of the molecule. With me? You will see this relationship if you make a model.