Coop work permit received without asking for it

[fi sola]

Hi, I am already in Canada, my program has an optional coop semester so I didn't apply for the coop work permit because It was not mandatory. But at the port of entry in Canada the officer give me a Work Permit(it has the institution as Employer, so I believe its a coop work permit) and I didn't ask for it. So can I use this permit if I decided to go for the coop semester or it's an invalid coop work permit?