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The aim of this article is to examine the singularity of two research-training devices, both of which are part of the same LéA (i.e. group of associated educational institutions). We examine the tension between epistemic (producing research results) and pragmatic (participating in professional development and producing resources for training) aims. These devices are presented in the general economy of the EvalNumC2 LéA, and then each of them is described in terms of the theoretical framework that underlies its architecture. The first device concerns an approach in mathematics didactics, and the second device concerns the analysis of the work of a multi-skilled teacher. They are then compared with respect to 1) the object of investigation common to the concerns of the researchers and the teachers (the evaluation of students’ mathematical knowledge), 2) the groups’ tools that are used and 3) the modes of collaboration that exist between each actors.