I myself cannot explain it but there is a GrisshamDevian1 twitter account I checked it and I don't exactly know the reason why it redirects to sameme's Twitter account since they do have a different username and I don't think you can have a custom link in Twitter especially a change in your username.  Maybe there is a deleted tweet in that thread that's why the link just redirects you to the thread or some. @OP if you want to tag both users you should explain the part as well on how GrisshamDevian1's link is redirecting to sameme's account.