I send messages to different users. When I switch from a user 2 to a user 1, then sometimes the message that I sended to user 2 is shown in the list of messages to user number 1. 

It is posible to reproduce this by switching between the tow users (somethimes I have to switch many time to let this bug accoures).

I postet a screenshot in the german forum https://moodle.org/mod/forum/discuss.php?d=404225