Thanks for the feedback.
The only problem is that the profile I want to merge into and again assume is "Admin_dup1". According to your suggestion I would have to open the "Admin" profile and go to the Merge User tab which does not exist for that profile (supposedly since it is the main administrator's profile). In other words, I can merge "Admin_dup1" into "Admin", but not "Admin" into "Admin_dup1".
[Also, is there any written documentation on merging users? I couldn't find it anywhere.]
Thanks.