IfJ is an indefinite signature matrix, then there exists aJ contractive holomorphic matrix valued functionW(z) in the open unit disc which can be expressed as a left Blaschke-Potapov product:W(z)=B (l)(z), but not as a right Blaschke-Potapov product:W(z)=E(z)B (r)(z), whereB (r)(z) is a right Blaschke-Potapov product andE(z) is a so called Arov singular matrix function. In factB (l)(z) may be chosen to obtain any Arov singular matrix functionE(z) in the second representation. This phenomenon and multiplicative representations of Arov singular functions are discussed.