So-called ‘fake’ or derived geminates differ in the extent to which they behave like lexical geminates, both across and within languages. Data that enable us to study the gestural as well as the durational properties of fake geminates can shed light on their status as long consonants or clusters, and on the effects of any degemination rules present in the language. Our focus is on Standard Dutch, which has been said to exhibit categorical degemination of derived identical consonant clusters. The specific interest is in the post-lexical gemination of /r/, which involves gesturally strongly distinct allophones in the language, such that the members of /r#r/ sequences are identical phonologically, but not phonetically. Ultrasound data from 8 speakers of Standard Dutch show that fake geminate /r#r/ sequences present combined articulatory characteristics of coda (bunched approximant) and onset (uvular fricative or alveolar tap) allophones, which can be captured in terms of gestural overlap or ambisyllabicity. At the same time, however, concatenated /r#r/ does not show an increased duration relative to singleton /r/. These results suggest that Dutch degemination does not involve categorical segmental deletion, as previously suggested, but instead it has constraints on phonetic consonant duration that limit temporal gemination. Such specific duration constraints have a more general role to play in any account of gemination, as accumulating evidence suggests that fake geminates at word boundaries tend to behave as consonant clusters, subject to constraints on degree of overlap.