javascript files loaded twice...

I am testing my app w Rails 2.0.2, and the loading log shows that the
prototype .js files loaded twice

http://0.0.0.0:3000/
..... images files loaded
http://0.0.0.0:3000/javascripts/application.js?1197932385
http://0.0.0.0:3000/javascripts/builder.js
http://0.0.0.0:3000/javascripts/builder.js?1197932385
http://0.0.0.0:3000/javascripts/controls.js
http://0.0.0.0:3000/javascripts/controls.js?1197932385
http://0.0.0.0:3000/javascripts/dragdrop.js
http://0.0.0.0:3000/javascripts/dragdrop.js?1197932385
http://0.0.0.0:3000/javascripts/effects.js
http://0.0.0.0:3000/javascripts/effects.js?1197932385
http://0.0.0.0:3000/javascripts/slider.js
http://0.0.0.0:3000/javascripts/slider.js?1197932385

in my layout I am using only :
<%= javascript_include_tag :all, :cache => true %>

what could be the source of that particularity...
thanks for your suggestions
erwin