  We exploit the key concepts of the augmented version of superfield approach
to Becchi-Rouet-Stora-Tyutin (BRST) formalism to derive the superspace (SUSP)
dual unitary operator (and its Hermitian conjugate) and demonstrate their
utility in the derivation of the nilpotent and absolutely anticommuting
(anti-)dual BRST symmetry transformations for a set of interesting models of
the Abelian 1-form gauge theories. These models are the one (0+1)-dimensional
(1D) rigid rotor, modified versions of the two (1+1)-dimensional (2D) Proca as
well as anomalous gauge theories and 2D model of a self-dual bosonic field
theory. We show the universality of the SUSP dual unitary operator and its
Hermitian conjugate in the cases of all the Abelian models under consideration.
These SUSP dual unitary operators, besides maintaining the explicit group
structure, provide the alternatives to the dual-horizontality condition (DHC)
and dual-gauge invariant restrictions (DGIRs) of the superfield formalism. The
derivation of the dual unitary operators and corresponding (anti-)dual BRST
symmetries are completely novel results in our present investigation.
