Model Validation only considers the first referenced Respository

While validating a model, only the first repository listed in the .system file is validated. Referencing multiple repositories within one system should be allowed, right?

Code from DMLSolver.java:

  // from system model navigate to repository model and validate it
  if (!sys.getAssemblyContexts().isEmpty()) {
     Repository repo = sys.getAssemblyContexts().get(0).getEncapsulatedComponent().getRepository();
     this.validateModel(repo);
  }