this article is not exactly what I need. It says "The system will sequentially go through all the additional designs, looking for the requested file". I realised, that if I have two versions of file with same name in different additional designs folders ezPublish always finds one and ignores the other.
Basically my question is in what order ezPublish searches AdditionalSiteDesignList. My experience is that this order do not depend om the order that these designs are listed in .ini file