Eyevet,
to answer your question, yes, this ten bills may have been deposit in a bank without being send to the Bank of Canada for destruction. They can be "lost in transit" which means, they have been send to an other bank or regional or main branch and sleep somewere in a vault. I will give you a scenario.
Mr. X deposit an UNC 1914 500$ in Small-town-somewhere-in-Canada. Assuming that the teller accept the bill and make a deposit in a regular account. this bill will travel with the rest of day cash and will be put in the vault until there's a pick up ( banks don't keep a lot of cash) and will be send to the regional branch. The bank employee that receive this bill and count the amount of money at the regional branch will be probably unable to put it in the computer and will count it as a "cash flow" and put it in the vault with the rest of "uncommon bills" like 1$, 2$, 1000$. The story told me that the bank employees are lazy and don't clean very often the vault. They usually finished in a casemate without seeing light during years...until somebody decide to clean up this mess. Then those bills are send with rest to the main branch where they are count, all serial numbers are put in a computer, they are checked and selected "in" or "out". If they are out, they will be send to the Bank of Canada, if they are in, they will remain in circulation and send back to the banks, but you must understand that a bank employee not knowing paper collecting can keep this bill as a regular issue with another " cash flow" and will be send with the 100$ bills. Bank of Canada notice are not followed as a bible...it is common to find new 1$ or 2$ bills in a vault. They just sleep with the "cash flow".