This article presents the results of regional documentary research concerning two publications by Josias Braun-Blanquet and Aimé Luquet from 1926. Each contains numerous names of associations and alliances that were previously considered homonyms of equal age in the International Code of Phytosociological Nomenclature (Art. 33). We show that Braun-Blanquet's publication predates Luquet's, and draw nomenclatural conclusions. We discuss several alliances that are widespread in Western Europe and were published by these authors or others in the same year: Adenostylion alliariae, Nardion strictae, Cardamino-Montion, Genisto pilosae-Vaccinion, Arrhenatherion elatioris, Caricion nigrae, Sphagnion medii, Fagion sylvaticae, Calamagrostion arundinaceae, Festucion variae, Piceion abietis, as well as their type associations. The discussion focuses on their nomenclatural status under the ICPN and how they are included in the current European classification (EuroVegChecklist) and in the Prodrome of French vegetations, according to their syntaxonomic concept. Taxonomic reference: WFO (2025). Abbreviations: Art. = ICPN article; CLF = Clermont-Ferrand university herbarium; EVC = EuroVegChecklist; EVCC = European Vegetation Classification Committee; GPN = IAVS Working Group for Phytosociological Nomenclature; ICPN = International Code of Phytosociological Nomenclature; MPU = Montpellier university herbarium; PVF1 = Prodromus of French Vegetation, first version at the level of the alliance; PVF2 = Prodromus of French Vegetation, second version at the level of the plant association.