Shouldn't it be the first address?
One is
For extensions including: work permit extension, open work permit extension
Case Processing Centre in Edmonton
Immigration Refugees and Citizenship Canada
c/o Work permits/Same employer, Station 202
9700 Jasper Avenue NW, Suite 55
Edmonton, AB T5J 4C3
because it clearly mentions-for extensions...and now on the site it is ...
Address the envelope as follows:
- Student work permit extensions (includes co-op, internships and post-graduation work permits)
Send your application to:
Case Processing Centre in Edmonton
Immigration Refugees and Citizenship Canada
c/o Student work permits/Same employer, Station 202
9700 Jasper Avenue NW, Suite 55
Edmonton, AB T5J 4C3
???