The development of vertical instabilities in elongated plasma is one of the major concerns for present and future fusion plasma experiments. During Vertical Displacement Events (VDEs), currents can flow partly in the plasma outside the last closed flux surface and partly through the vacuum vessel and other parts of the magnetic boundary system. These halo currents can induce mechanical stresses and eventually lead to serious damages to the experimental device. Moreover, asymmetries can develop in the toroidal distribution of halo currents worsening their detrimental effect. In order to build safely future devices, experimental data from present ones have been collected and analysed, building single-machine or multi-machine scalings. The complementary approach of implementing numerical codes able to model and simulate disrupting plasmas is also being pursued. The problem of disruptions and of their avoidance, or at least mitigation, is very complex since technical construction details of the single device are very tightly mixed with general physical laws to determine the final result. Recent Alcator C-Mod data show for example that many differences in halo current amplitude and symmetry were induced by the change of the divertor structure. It is then clear that to extrapolate to ITER results of present machines it is very important to understand which characteristics and trends are machine independent and which are specific to a single device. The aim of this work is to compare some recent halo-related data from two tokamaks, JET and ASDEX-U, paying particular attention to the use of homogeneous analysis tools and definitions.