Marco Krohn:
As user WikiED probably does not know about commons he probably did not know that his upload caused problems in several articles. Is there anything one can do about avoiding such problems, e.g. is it possible to force a load from commons? Something like commons:Image:Tiger.jpg unfortunately does not seem to work. Also in the upload form it would be helpful to get a warning about a potential naming conflict.
This is bug 889: http://bugzilla.wikipedia.org/show_bug.cgi?id=889
One way to deal with such cases at the moment is to upload the file to Commons under a more unique filename and replace the links.
Erik