This paper investigates the interpretation and processing of simple transitive Catalan sentences with multiple negative expressions experimentally. Our results provide empirical confirmation that Negative Concord (NC) is the preferred and faster interpretation for negative sentences that either omit or contain the overt negative marker no 'not'. However, they also reveal that, in contrast to traditional descriptions of Catalan and independently of particular favoring contexts, a non-negligible amount of Double Negation (DN) readings arises, mainly when the negative marker co-occurs with pre-verbal Negative Concord Items (NCIs), and when these NCIs have a complex DP structure. Our results further suggest that two populations could be distinguished: one for whom the negative marker is optional and leaves the favored NC reading essentially unaffected, and another where the co-presence of no significantly increases DN readings. We account for these findings within a micro-parametric approach that features ambiguous NCIs (non-negative vs. negative) and a possible ambiguous negative marker no (negative vs. expletive) variably available for Catalan speakers. The nuanced empirical NC landscape that our experimental work reveals serves to stress the importance of taking DN readings into consideration for a better understanding of the nature of negative constructions in Catalan and cross-linguistically.