Our recent experiences shape our perception, a concept known as sequential bias. While extensively studied in the visual domain, this phenomenon remains largely uncharted in time perception. The present study examined how task relevance and task types influence temporal sequential biases. Employing a dual-feature random dot kinematogram (RDK) - duration and direction - we asked participants to encode both features in each trial and report one based on a post-cue. The preceding duration-report trials were regarded as task-relevant responses, while the previous direction-report trials were considered task-irrelevant responses. Additionally, we used the time discrimination task in Experiment 1 and the duration reproduction task in Experiment 2. Both experiments revealed a significant sequential bias: durations were perceived as longer following longer previous durations, and vice versa. Moreover, we found a decisional carryover effect in both tasks. Intriguingly, in the discrimination task (Experiment 1), the sequential effect showed no significant variation whether following timing or direction tasks. Conversely, in the reproduction task (Experiment 2), the sequential effect was more marked following the same timing task than the direction task. These findings indicate that the sequential bias in time perception is likely modulated by working memory processes that link sensory representation and task-specific decision-making.