Hi,
I highly doubt it. A direct quote from cic website;
" A work permit under the PGWPP may be issued for the length of the study program, up to a maximum of three years. A post-graduation work permit cannot be valid for longer than the student's study program, and the study program must be a minimum of eight months in length. For example, if you graduate from a four-year degree program, you could be eligible for a three-year work permit if you meet the criteria. If you graduate from an eight-month certificate program, you would be eligible for a work permit that is valid for no more than eight months. "
Based on the quote above, I think you can be considered for the exact length of your program [1.5 years] or miraculously 2 years. Never really heard of 1.5 years PGWP to be honest.