clembo The position of a drill hole can in some cases give clues to the reason it was done in the first place.
Look at the design and then the hole or holes. Two holes dead center and you have a button. One hole dead center and you have a British Bank cancellation of the colonial era.
One hole top center in relation to the picture on the coin and you probably have a pendant but one at the bottom of the coin would be either a cancellation or a protest against the ruler. French coins are often seen with holes positioned to stand the King on his head in protest. A hole through the date or denomination or on the sides of the coin are likely cancellations. If the coin has edge notches or scratches and a hole it is also likely a cancellation.
But in any even check the coins and if you want send me photos. I never mind looking at coins and can give you an answer in a few seconds on most coins.