  Frames in a separable quaternionic Hilbert space were introduced and studied
in [17] to have more applications. In this paper, we extend the study of frames
in quaternionic Hilbert spaces and introduce different types of duals of a
frame in separable quaternionic Hilbert spaces. As an application, we give the
orthogonal projection of $\ell^2(\HH)$ onto the range of analysis operator of
the given frame, in terms of elements of canonical dual frame and elements of
the frame in quaternionic Hilbert space. Finally, we give an expression for the
orthogonal projection in terms of operators related to the frame and its
canonical dual frame in quaternionic Hilbert space.
