I can understand italian, but can't speak/write it, so here's my answer in english - hope you understand.
At the moment the rpm just places it's files where they should be - if they're already there rpm will bail out.
I think i'm going to fix that ed2k issue with creating /usr/bin/ed2k-amule, moving /usr/bin/ed2k from the xMule package to /usr/bin/ed2k-xMule and placing a symlink that points to on of those - depending on the users choice. It would clearly break the xmule rpm which can't uninstall ed2k after that.
I'll post that to the dev forum as well and wait for them to decide what to do.
For now you can simply rename /usr/bin/ed2k to /usr/bin/ed2k-xmule. After that you can install the aMule rpm without problems.