Possible 1964 SMS 25c And 50c?!?!?

For a while, I posted a new thread, about a SMS 1964 quarter... everyone wasn't exactly sure if it truly was a 1964 SMS quarter(The images weren't too great)... Since I found this quarter in my great grandfather's huge collection of coins, I didn't know either. But, then, after a while, it hit me to look for the other coins too...(Like the half dollar 1964 sms coin as well). Well, when I open the Half dollar silver bag that my grandfather sorted them into, STRAIGHT AWAY, I found 6 1964 Half dollars... 4 of which looked exactly like a sms set coin. All of the 6 coins were clean, but these 4 had a gloss to it, not exactly proof(Not close to it at all, actually). But, it was VERY clear, the difference of these coins. Now, all of these coins are left with my grandfather back at his place, but I do have the quarter(s), and I'll try to get images of the 50c sms set coins ASAP. But, do you any of you guys think that it could be a possibility that my great grandfather knew about these as well? Some background info: my grandfather and great grandfather never even had a great relationship WHATSOEVER, and my grandfather didn't even know about these coins until AFTER my great grandfather passed away. Apparently the coins were sorted into groups(But, not many), but not into type of coin; but, into groups that my grandfather didn't understand at the time. It wasn't until I started looking deeper into these coins, and looking at these $800 of FACE VALUE of SILVER coins that I came across these specific coins.(Once again, I'll try to get images of the half ASAP)... But here are the images of the quarter: