In this paper we propose that spontaneous gemination in the dialects of Cyprus and Kos is part of the Multiple Parallel Grammars (co-grammars) for lexical gemination in Greek. Stress position is irrelevant to spontaneous gemination. Instead a disyllabic trochaic domain is formed on one of the prominent positions of the word edges, the word-initial or word-final syllable. Gemination of the onset of the complement syllable highlights the prominence of the head of this domain, in contrast to its complement. The gemination of the head onset is a deviation due to well-established phonotactic constraints of the language. Nevertheless such gemination also projects the prominence of the head syllable. Variation between the dialects of Cyprus and Kos is the result of the varying directionality of the trochaic gemination domain, i.e., word-initial for Cypriot Greek but word-final for Kos. Otherwise the constraints of the co-grammar of spontaneous gemination are the same for both dialects.