I fully agree to what you say. I myself have seen the case of rake sharing between 13011 and 53047 as mentioned on the nameboard. I have also seen the common nameboard of 12337/38/39/40/41/42. But I also didnot ever see the boards tagged 'Reserved for Durgapur', 'Resreved for Andal', 'Reserved for Asansol' on the coaches of 53047 before yesterday. I saw these boards on the coaches of 53047 yesterday. Perhaps the boards were not removed at the Howrah coaching yard yesterday. This made me think of rsa between 12337/38/39/40/41/42 and 13011/13012/53047/53048. Maybe there are a total of 4 rakes dedicated for all these trains. I donot have any proof to show you at present, but definitely I will take pictures if I see this again.