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.

For centuries, herbarium specimens were the focus of exchange in global botanical networks. The aim was the ‘complete’ registration of the flora, for which ‘complete’ collections in botanical institutions worldwide were considered to be a necessary basis, although this ardently sought-after ideal was never achieved. The study of colonial plants became a special priority of botanical research in the metropolises. With knowledge of the many treasures of the plant world considered the key to securing wealth and power, political and economic interests influenced both the organization and the subject matter of scientific research. After the German Reich began annexing colonies in the 1880s, legal regulations established Berlin's botanical institutions as the research centre on colonial flora. They also became a clearing house for plant material from overseas. Berlin-based curators selected duplicates of herbarium specimens from the German colonies, distributing them to other botanical institutions throughout Germany. More importantly, duplicates became a form of currency in trans-imperial networks, which relied on reciprocity. In exchange for duplicate German colonial herbarium specimens, the Berlin institutions received vast quantities of botanical samples from their British, Dutch, French and American counterparts.

The issue of duplicates and duplication in ethnographic collection is frequently regarded as a process that begins and ends in the museum as a fundamental act of the process of curating. In contrast, this article maintains, this practice occurred all along the chain of collecting, where indigenous artefacts operated as items of exchange in the context of the colonial encounter. Using the example of German New Guinea, the article maintains that epistemological concerns, as symbolic currency both in terms of inter-museum exchange and in terms of contributing to individual and institutional prestige, guiding ethnographic intuitions had little influence on colonial resident collectors. Colonial residents, who resented the heavy hand of colonial and museum officials in Berlin, infused duplication with their own desires, which included commercial gain or the conferment of the many German state decorations. The colonized indigenous population benefited from the increasing demand for their material culture, which provided valuable items and bargaining chips in the emerging colonial exchange. Duplicates are identified as doppelgängers to explore the political tensions that emerged in connection with duplication among museum officials and European and indigenous colonial residents.

The nineteenth-century museum and auction house are seemingly distinct spaces with opposing functions: while the former represents a contemplative space that accumulates objects of art and science, the latter provides a forum for lively sales events that disperse wares to the highest bidders. This contribution blurs the border between museums and marketplaces by studying the Berlin Zoological Museum's duplicate specimen auctions between 1818 and the 1840s. It attends to the operations and tools involved in commodifying specimens as duplicates, particularly the auction catalogue. The paper furthermore contextualizes the museum's sales in a broader history of duplicate auctions across Berlin's collection landscape.

In the late nineteenth century, the anthropology curators of the Smithsonian Institution consulted their cataloguing systems and storerooms, assessing specimens in order to determine which could be designated as duplicate specimens and exchanged with museums domestically and abroad. The status of ‘duplicate’ for specimens was contingent on conceptions of similiarity impacted by disciplinary classification praxis, with particular emphasis on object nomenclature and formal attributes. Using rattles from Haida Gwaii collected between 1881 and 1885 by James Swan for the Smithsonian Institution, this article explores how anthropology curators designated rattles as exchangeable duplicate specimens. It considers cataloguing and spatial arrangements, as well as changing populations and formal characteristics of rattles, in order to explore how similarity was operationalized in the museum to produce duplicate anthropological specimens.

The article considers how the use of duplicates and the practice of photography interacted in museums of ethnography, contributing to the ambivalent framing of ethnographic objects as items that can be both scientific specimens and works of art. It focuses on the Musée d'ethnographie du Trocadéro in Paris and on the key period of its reorganization between 1928 and 1935, which was central to the institutionalization of French ethnology. By examining the place of duplicates in this museum, as well as the major role attributed to photographs of objects and their materiality, the paper shows that these others of the ethnographic artefacts, often considered separately from their originals, still participated in the same project: the development of the museum and its growing cultural influence. While the duplicates positioned the museum in the various networks of the scientific community, the photographs appealed to the avant-garde, amateurs, African and Oceanian art dealers and the general public.

This article situates the collecting practices of museums of natural history in the nineteenth and early twentieth centuries in dialogue with similar practices amongst societies in the Pacific by focusing on how European curators, dealers in natural history and Pacific Islanders shared a common fascination with Spondylus shells. In particular, this article examines the processes for turning Spondylus shells into unique or duplicate specimens. Spondylus shells were crucial for regulating gift and commercial exchanges in the societies of both regions. Famously, the anthropologist Bronisław Malinowski claimed that these shells were an essential element of the gift-based kula exchange, which helped him distinguish Western capitalist society from less developed societies without commercial trade. Yet Spondylus shells were also collected and exchanged as gifts amongst British and European naturalists in this period, performing the same roles as in Melanesia. In addition, such gift exchanges could only come into being thanks to the actions of commercially motivated dealers, located both in the Pacific and in Europe, who were the suppliers of these shells both to Melanesian participants in the kula and to Western natural historians and collectors. These observations call into question earlier arguments that equate modernity with the rise of commercial capitalism. It is instead claimed that commercial and gift exchanges were intricately connected and reliant on each other throughout the period, whether in the worlds of Western museums or in Pacific archipelagos. The act of turning Spondylus shells into unique or duplicate specimens was the key tool for regulating these exchanges.