What mechanisms underlie aspirate dissimilation: perception or motor planning errors (Garrett 2014)? In answering this question, aspiration dissimilation has been shown to be a gradual phonetic process on post-aspirated and preaspirated stops (and therefore likely the result of motor planning errors; Jeatteau and Hejna 2015). Previous experiments, however, did not test the phenomenon in the environment of two post-aspirated stops, which allowed for alternative explanations. The paper aims to fill this gap: I test the duration VOT of two subsequent aspirated stops. The results suggest that aspiration dissimilates (shortens) when another aspirated stop precedes, even in languages with only post-aspirated stops (such as Georgian).