Hi Jitendra,
I am sorry for my late reply. Since the question was marked as "Not Answered" I thought I should still reply. As Bjoern stated, each service implementation project in SMP/IGW provisions a single OData service. This is by design.
One can naturally question then why we allow adding another model into the project. Main advantage of this, is to copy entity sets from one model to the other. But I have to admit that it is not very practical as there are other ways of doing this.
I hope this helps.
Regards,
Mustafa.