The coins are not rare at all. Over 400 million of them were made. Their value is pretty much determined buy the melt value (price of silver) which today is about US $11 (assuming they are both 1964 coins). They can be worth more if they are graded and receive a high grade. This is an example of value vs. grade:
Chances are they are business strike coins and not worth much above melt value.
The real value is the entire set (don't remove the coins). The only way to estimate its value is to find others that sold (ebay is a good place to look) or take it to an appraiser who can examine it in person.