A two-nucleon potential of the following form has been studied: the one-pion exchange potential (OPEP)+two finite rectangular cores, corresponding to the central and the tensor part of the OPEP, both cores having the same range. Two solutions fitting the deuteron properties have been found, one with strongly attractive, the other one with repulsive cores. The last can also be chosen so as to fit experimental data on triplet even scattering up to 150 MeV.