  In this study, we generalize double tangent bundles to double jet bundles. We
present a secondary vector bundle structure on a 1-jet of a vector bundle. We
show that 1-jet of a vector bundle carries two vector bundle structures, namely
primary and secondary structures. We also show that the manifold charts induced
by primary and secondary structures belong to the same atlas. We prove that
double jet bundles can be considered as a quotient of second order jet bundle.
We show that there exists a natural involution that interchanges between
primary and secondary vector bundle structures on double jet bundles.
