A single-entry visa allows you to enter Canada once. An official from the Canada Border Services Agency will check that you are eligible to enter Canada when you reach the port of entry. To enter Canada again after leaving during your permitted stay, you need a new visiting visa. Whereas, You are permitted to enter Canada several times while your visa is valid if you have a multiple entry visa. A multiple-entry visa can be used for up to ten years, or until one month before the passport or re-entry visa expires, whichever comes first.