I have ran into this too. Most likely you have a Secretary who has
several Boss's calendar's she takes care of. In these situations, you
normally have a Exchange environment and that secretary has the Boss's
mailboxes in her MAPI profile opening as additional mailboxes. This by
default puts them in her My Calendar's section. To get them out, unmap
the mailbox, then have her "Open a Shared Calendar...". This will put
the link in the "Other Calendar" section. You can then re-map the
mailbox and it will ALSO put the link up top in the My Calendar
section. Very annoying, but only way it works. If she clicks his name
in the Other Calendar section, the title bar shows appropriately; if
she clicks the name in the My Calendar section, it still shows the
default text.

I've run this gambit before, this is the best your going to get, sorry.