No expert but I think its machine doubling

Its hard to make out the stamp with your picture, some merchants stamped the coins back then others for maybe a special year ? The coin is considered damaged un-gradable, but not un-collectable some people collect these coins

Yes I try to avoid those coins its like throwing money in a hole, same as coins that were made into jewelry most are considered scrap bullion

If you have a Charlton Canadian coin book, I found it on (page 106) of the 2019 - 72 edition

It was a wild guess on my part SP67.
Here's one I have I think it may be double indent

I think its called an indent strike with a partial Brockage by the looks of photo

Looks like parking meter or a machine coin roller.

They have value not sure what they sell for

Looks like a SF obverse but a good coin to watch out for

Check the 1954 for NSF obverse

It has no dirt or crud on it for something that has circulated that much, I agree it has been cleaned at one time in its life

I agree with others get familiar with coins what their worth study the grade system a bit before you decide on pricing on coins. To have someone estimate and grade your coins ( I believe ) is around $85.00 an hour Canadian

I'm not an expert on error coins, but it sure looks like its real to me just by looking at other pictures of a real one. The only thing I see is the color looks to be odd

Also first time for me I'll be checking them now

I'm with Bill it would cost more to get it graded than what it might be worth, if left in mint package it might have had a bit of value for a collector that collect mint package error's.