>is it safe to get rid of repeted favicons?
favicons are just storing the little pictures you see in internet explorer next to the URl, you can delete them, they will likely come back.
Injected advertising leaves all kinds of garbage on the IE temporary files, mostly harmless....any web site that has advertisments on it can do this..welcome to the age of electronic garbage ;P
(You can trash the temporary files in IE under the tools menu you know.., has the advantage you won't accidently delete something important, and you can set it to always delete them automaticly when you close IE)