This article offers a study of French nouns referring to humans, such as pneumo- logue or radiologiste, which contain the sequences logue or logiste. At first glance, these components appear to form two competing morphological rules forming the names of specialists in the domain indicated by the base noun (cf. radiologue and radiologiste). Our study aims to determine whether nouns constructed with logue and logiste display competition of morphological rules, that is, whether these nouns are synonymous and formed on the same type of base and comparable construc- tional schemas. We examined over 1,000 nouns, from the TLF and from the frWaC corpus. We followed a dual line of inquiry, semantic (analysing the semantic values associated with these nouns, aiming to identify to what degree pairs are corefe- rential) and morphological (aiming to determine whether logue and logiste are components of morphological rules, specifically neo-classical formation rules, and whether these rules do indeed select the same type of base, as they appear to). Our study required the comparison of nouns with logue and logiste with nouns with logie, naming corresponding disciplines (allergologie, dermatologie, égyptologie, glaciologie). The results have led us to conclude that nouns with logue and logiste no longer share the same semantic properties in contemporary lexicon, a fact which is reflected in their morphological formation, which is no longer based on neoclassical composition.