Di-electron production in N+N collisions at Ekin < 5 GeV/u was studied previously by the DLS collaboration  and have been available for about 10 years, although with limited statistics and mass resolution. Microscopic transport calculation, hovewer, never succeeded to explain the experimental data satisfactory until a strong bremsstrahlung contribution in n+p interactions has been recently predicted within the framework of a covariant One Boson Exchange (OBE) model . The authors choose the free parameters of their theory similar to the ones used in , but the restoration of the gauge invariance (for n+p) has been realized in a different way. This leads to different types of the form factors and quite different results. Indeed, it is found to differ by a factor of 4 for n+p interactions, but also by a factor of about 2 for p+p reactions at 1 GeV kinetic beam energy compared to the ones of Ref. . As the NN bremsstrahlung process as included in the new OBE calculations from Kaptari et al.  is widely discussed in context with the interpretation of the C+C data, we should have a closer look on the comparison of these calculations to the HADES data for p+p and n+p interactions.