TEmbeddedWB repeats copy action when program closes

Question

I execute the following code to copy the whole text from a TEmbeddedWB to the clipboard:

EWBH.ExecWB(OLECMDID_SELECTALL,      OLECMDEXECOPT_DODEFAULT);
EWBH.ExecWB(OLECMDID_COPY,           OLECMDEXECOPT_DODEFAULT);
EWBH.ExecWB(OLECMDID_CLEARSELECTION, OLECMDEXECOPT_DONTPROMPTUSER);

However, when closing the program after this, something automatically copies the same content AGAIN. I have checked that this code is NOT executed again, so it must be something else (TEmbeddedWB?) which does the copying when the program closes.

Is there something wrong with the code above? How can I prevent the additional copying when the program closes?

EDIT201404011858: It seems that the problem does not occur if after the execution of the above code something else is copied to the clipboard.