The United States Code is riddled with “duplicative delegations”—delegations in separate statutes or statutory provisions that may reasonably be construed as granting the same regulatory authority to different agencies. In this Article, I look at real-world regulatory dynamics to determine how duplicative delegations arise, how they impact the design of legal and regulatory institutions, and how they alter the balance of powers among the branches of government. I show that duplicative delegations are generally either unintentional or incidental to other congressional aims. Nevertheless, they are pervasive. If all agencies acted on their duplicative authority, duplication and conflict would seriously disrupt the regulatory system. To avoid such an outcome, Congress and the White House have crafted an array of “antiduplication xinstitutions” that screen out duplication ex post and put significant downward pressure on agencies to avoid duplication on their own. Normatively, I argue that, because the costs of avoiding duplicative delegations ex ante are significant, Congress and the White House should rely on these comparatively cheaper ex post institutions to screen out duplication. However, because these ex post institutions also have their costs, it is efficient to let some duplication persist. As a separation of powers matter, I show that, through duplicative delegations, Congress provides the executive a menu of agencies from which to choose which agency should perform a particular regulatory task. Descriptively, the President and agencies routinely divvy up tasks and set jurisdictional boundaries among agencies with duplicative delegations. Normatively, because of the executive branch’s comparative advantage at allocating tasks among agencies according to their expertise and policy interests, I propose an interpretive default rule under which courts would defer to executive arrangements reconciling duplicative delegations.