I made a post today and tagged 5 people.  The first two worked fine, but on tag 3, 4, and 5, it changed the text of the tag (and the tag itself) to the 2nd person tagged.

So, if I write a post tagging @user1 @user2 @user3 @user4 and @user5, it changes it to @user1 @user2 @user2 @user2 @user2.  The tags after #1 all go to @user2.