This paper traces the uses of comparisons between Algeria and Libya, two colonies that shared a peculiar parallelism. Side by side, both underwent particularly virulent forms of colonial rule that set them apart from their North African neighbors, facing prolonged wars of conquest, waves of European settlement and a distinctive form of administration that tied them closely to Paris and Rome respectively. This similarity was no coincidence, as the Italian colonial project in North Africa from 1911 onwards borrowed from the earlier French conquest of Algeria, and Italian and French bureaucrats shared tips and legal expertise on controlling unruly Muslims. For some of them, the two ‘Latin sisters’ were essentially running one common project with two empires: returning North Africa to its former Roman glory through a combination of mass agricultural settlement programs and aggressive archaeological excavations. On the other hand, this proximity could also be toxic. French officials were keen to distance themselves from Italian colonialism at times, especially after the advent of Mussolini’s fascist regime, worried that news of atrocities in Libya might boomerang back to their own North African possessions. Bad neighbors could expose the weaknesses of colonialism at home, and for the administration as much as for nationalist politicians. Some of the earliest formal political mobilization in Algeria took place around the Italian invasion of Libya. For those who sought to improve the colonial system whilst appearing loyal to France, this strategy of emphasizing differences between French and Italian colonial rule worked well, because complaining about Italians was less risky and therefore a useful proxy for complaining about France. On the other hand, a more radical line of analysis, which became more influential in the 1930s, saw all European imperialism as one and the same. In this light, the narcissism of minor differences between the two empires obscured the systemic reality of European supremacy. Using archives in Algeria, Italy and France as well as a range of press sources, this paper argues that it was through comparing Algeria and Libya that people determined whether there was one colonialism or several.