I modifed the sample1service and renamed
How have you renamed it ? A service must have a unique contract identifier and a specific assembly. If you have multiple service in the same assembly, each service and contract must be in different namespace.
The Lego NXT dashboard uses MSRDS control panel service to read the assemblies in MSRDS bin folder and get all the services. It displays the "DisplayName" of the service.
For provided samples, the three services are defined in the same assembly, but in different namespaces. Each service has a unique contract and a unique display name.
[DisplayName("SimplySim NXT Sample1")]
public class Sample1Service : DsspServiceBase
Check that you have renamed your service following MSRDS convention and that you have changed the display name attribute.