HTML kod in widgets and footers messup

Can someone explain why the blogs mu theme messes up code in footers and widgets? it seem it’s not possible to use simple codes for i.e. banners in more than widget cause then that code gets picked up somewhere else in another widget..

To sum things up I can not place code in the footer with a regular link to the registration form since it picks up code from another html link in another widget.. (codes I use all the time on other sites using other templates so that is nothing wrong with them)