I know what you mean, I've got a few events like that where they have a bunch of registration options set up as separate events on RunSignUp but in reality most of 'races' on RunSignUp are all the same distance and start the same time, but they simply want the results to break things out by Athlete Type or Division.
One example is the Beast of Burden race I time (
see here). You'll see that they have a lot of registration options, but if you view the Results page and click on the dropdown box that "Overall Results" you'll see that I only have three "Overall Results" result sets (indicating that I set up only 3 races in ART), and all of the other result sets that were created on RunSignUp are created by checking "Include Division Results" under the Publish Results link in the Action Key tab of the timing screen.
In this race they did not have race day registration, they actually cut off registration a few days before the event. After registration was cut off, I pulled all teams in and used only one of the 'races' that was linked up to RunSignUp to host all participants in ART. Of course I set up Athlete Types and Divisions so that ART can break everything out correctly. Here is what the end result looked like: