Yes you may or you may not get 3 years PGWP.
See, I have heard so many cases about students getting students getting 1 year PGWP even after 2 years course or some students got 3 years PGWP after 1 year course or the case you're talking back to back PG certificate students got 2 years/3 years PGWP.
So in the nutshell, it all depends on the credit hours
for 3 years PGWP the credit hours of the study should be about 57 to 60 hours. If you can make it upto it, then you are good to go.
or,
According to CIC
If It's a combination of;
a) 1 year Diploma + 1 year Master Degree, or
b) 1 year Degree + 1 year Post Graduate Diploma.
2. You MUST complete your 2nd course within 2 years
of having successfully
pass-out the 1st course.
http://www.cic.gc.ca/english/resources/manuals/bulletins/2010/ob194.asp
Good luck!!