Abstract
In "Digital Doppelgängers and Lifespan Extension: What Matters?", Iglesias et al. argue that “some of the aims or ostensible goods of person-span expansion could plausibly be fulfilled in part by creating a digital doppelgänger”. Since person-extension aims are deeply heterogeneous, however, no single type of doppelgänger system is likely to suffice to meet all such needs. We propose a partial typology of doppelgängers—the family heirloom, the research archive, the public legacy, the project surrogate—and suggest appropriate training methods, design features and governing norms for each. Finally, we reflect on the implications of concurrent yet heterogeneous doubles for questions of personal identity.