The permanent preservation of objects in global custodianship is a captivating ideal that informs countless museums’ corporate identities and governs collection guidelines as well as politics. Recent research has challenged the alleged perpetuity of collections and collected items, revealing their coherence as fragile and dependent on historically, politically and culturally specific conditions. Duplicates offer an instructive point of entry to explore the idea of collection permanence, museum politics, and the mobility of museum objects. The history of duplicates, moreover, comprises a constellation of practises, concepts and debates that can be found in various forms throughout the intertwined histories of natural-scientific, ethnographic and artistic collections. This history, however, has rarely been questioned or explored. By introducing the issue of duplicates, this paper opens up a discussion that not only connects different forms of collections, but also situates the history of collecting institutions across the disciplinary spectrum within broader political, economic and epistemic frameworks.