  Superpositions of hierarchies of integrable equations are also integrable.
The superposed equations, such as the Hirota equations in the AKNS hierarchy,
cannot be considered as new integrable equations. Furthermore if one applies
the Hirota bilinear method to these equations one obtains the same $N$-soliton
solutions of the generating equation which differ only by the dispersion
relations. Similar discussions can be made for the locally and nonlocally
reduced equations as well. We give, as an example, AKNS system of equations in
$(1+1)$-dimensions.
