To Parnit, you can keep both, where you live in Canada if you live in a border city then I see no issues there, you are keeping your passport from India right?, if so then all you have to do is show your passpor with Canadian PR in canadian border and when you get into US border show your passport with US PR card, I see no problem. I was talking to a friend of mine because I am also in the same boat as you are. I am waiting for my Canadian PPR to get my PR here in Canada at the same time after 9 years I got my US PR approved and he told me that I can keep both just go in and out and that will work it out.
Now, My question to you is I am also trying to see if I can get my interview here in Canada, How did you manage to get your appointment transferred from India to Canada please your advise on that will be very much appreciated.
Thanks