Plasma collisions in magnetic fields play an important role in the acceleration of particles and radiation generation in astrophysical objects and in the high intensity laser plasma interaction. In laser-target interaction the expanding plasmas can be created with the Target Normal Sheath Acceleration mechanism, TNSA. The possibility to observe the Weibel filamentation in two inter-penetrating TNSA plasmas in an ambient magnetic field is studied theoretically and numerically in the present work. Relying on 2D3V Particle-In-Cell simulations and analytical estimates, the effect of the decreasing density profile coupled to the increasing flow velocity on the external magnetic field accumulation and the development of the magnetic vortexes is analyzed. It is demonstrated that with realistic TNSA profiles the plasma collision can lead to magnetic field accumulation and to the development of magnetic vortexes. These results are of interest for interpretation of the experiments which may be carried out in this regime on high intensity laser facilities.