Using a similar method to the MORI technique (Kanematsu, Mori, & Mori, 1996), we investigated effects of discussing and making a unified report by a pair of participants who were auditorily presented with partly-different stories without noticing that the stories were different. Twenty pairs of participants listened to 5 minutes stories simultaneously via headphones. The stories were taken from a TV detective drama, and the two stories were almost the same except for the motive of the crime about 40 seconds long. After listening to the stories, they were asked to recall them individually. Then they discussed the stories, and half of the pairs were asked to make a unified report (collaborative condition), and the other half of them to make reports individually (control condition). Finally, they were required to recall the stories individually a week later. The results showed that the participants in the collaborative condition recalled stories which were not actually presented more often than those in the control condition a week later, without noticing that they did not in fact listened to them. Effects of discussing and of making a unified report upon memory were discussed.