This Article analyses the recent divergence between the two European Courts on the application of ne bis in idem to double-track procedures from the perspective of judicial dialogue and constitutional pluralism. Although major efforts have been made towards convergence over the past decades, recent case law shows that the potential for conflict – and, possibly, incompatibility – remains wherever the incentive to follow the lead of one authority is insufficient. Pushed to find solutions by the resistance of certain national courts to their converging standards, the European Court of Human Rights and the Court of Justice have chosen very different paths to reach a similar, but not identical, compromise solution.