[O] C-C C-W (refile) makes copy when invoked in Agenda view?!

[M]

Hi,

I'm having a problem with the refile command (invoked by C-C C-W):

when I' using it in agenda view (for the selected line or as bulk command on
marked items), it creates a copy of the items at the new place, but leaves
the old ones in place (and thus creates unwnted duplicates)!

However, when I'm directly in an org-file and use C-C C-W, it moves the
selected subtree, as it is supposed to do.

How could it technically be possible, that the 2 same commands do different
things?
I read about an option org-refile-keep, but I can not find it with M-x
customive-variable.

I'm sorry - I don't know how to track this down for creating a minmal
example.

I'm using Aquamacs 2.5 on OS X 10.6 with org-mode 8.2
GNU Emacs 23.4.1 (x86_64-apple-darwin12.3.0, NS apple-appkit-1187.37)
 of 2013-06-14 on acs-trailblazer.ist.psu.edu - Aquamacs Distribution 2.5

Kind regards

Martin