  In this paper, we investigate some characterizations of dual continuous
frames and give some results about them. Also, we refer to the method of
constructing a family of duals through a fixed dual and show there exists a
one-to-one correspondence between duals of a continuous frame for Hilbert
$C^*$-module $U$ and adjointable operators $K$ from $U$ to $L^{2}(\Omega
,\mathcal A)$. Then we check the conditions that the sum of two duals of a
given continuous frame under the influence of adjointable mappings becomes a
dual of it and state some results about them.
