  As originally defined by Ashraf and Mozumder, multiplicative
(generalized)-skew derivations must satisfy two identities. In this short note
we show that, as a consequence of the simultaneous satisfaction of both
identities, a multiplicative (generalized)-skew derivation of a prime ring is
either a multiplicative (generalized) derivation (i.e., not skew), or a
generalized skew derivation (i.e., additive). Therefore only one of the
identities should be taken in the definition of multiplicative
(generalized)-skew derivations in order to get a new class of derivations in
prime rings.
