Thats right, In some cities and passport offices they require the evidence of approval and immigration services, so you just can present the approval notice. that is just for their refrence that you are under process of immigration or visa services, not faking for something or wasting their time.....(that was told by police official)
Go ahead and get the certificate.....
Actually i am kind a scared from police clearance word.. it wasted my almost three week..otherwise i can have my interview scheduled in JULY.. so be careful while filling the Missalaneous form(EAP-2) for passport office, dont forget to fill country's name(USA)...even if you dont see any column for it.