I cant reproduce by logging in at :
www.alofonia.com/
but I can reproduce by logging in at:
alofonia.com/
This is to be expected ans is the way sessions work.
The session ID is tied to a cookie that is created on the clients machine. Cookies are domain specific.
To a cookie, the domain "www.alofonia.com" is not the same as "alofonia.com" so a different session cookie, tied to a different session ID is created for each one.
You should redirect users who come to p[age using the domain "alofonia.com" to "www.alofonia.com"