We have fabricated and tested Josephson tunneling structures made of two stacked Nb/Al/AlOx/Nb long junctions in which the thickness of the intermediate electrode is less than lambda(L). We report the observation of two phenomena: a considerable decrease of the Swihart velocity and a small but finite voltage jump of the quasiparticle voltage of one junction whenever the other one switches from the superconducting state to the normal state or between dynamical states.