Yes you can use it. It doesnt matter if its more than 2 yrs old as long as you can prove you did the test. All CIC looks for is you have the competency. Look at it like this, Once you learn to read, write , speak and understand english, its not something you can forget. Although going by the same argument, its kinda stupid that CIC asks for this document even though they know you did these for PR.
CIC is funny.