The production ofb- andt-quarks ine+e− collisions may be appropriately investigated from the observation of like-sign dileptons. We estimate the branching ratios and the average lepton energies in semileptonic decays of heavy particles, taking into account both cascade decays and the mass-mixing of neutral mesons. They are found to be relatively large. Then, we consider the angular distribution and correlations for events wheighted by powers of the lepton energies. These quantities (moments) have a transparent decomposition, where each factor corresponds to a dynamical step in the production of dileptons. Our computations suggest that the study of like-sign dileptons along these lines would provide interesting information on the heavy quark fragmentation and decay.