The first one is to be used to produce the paper copy (which will be distributed to CATS'02 attendees), and the second is used to produce the electronic version (which will appear in ENTCS).
Note that prentcsmacro.sty has to be renamed to entcsmacro.sty to work properly; hence this is really two different versions of the same file, and hence the name has to be the same for it to work properly with the genetic package.