This paper discusses the evolution of learning engagement patterns and learners' profiles across sequential iterations in two MOOCs. Both courses were relatively stable over time from the demographic point of view, with punctual but notable variations. In both cases, registrants who completed the course tended to decrease in proportions over time as the proportion of bystanders increased, but they were nevertheless responsible for most of the course activity in terms of video consumption or quiz submission. We observed that the statistical associations between engagement in the course and learners' demographic variables were more acute in specific tracks, suggesting that the impact of sociocultural and socioeconomic variables on engagement patterns strongly depends on the context of the course.