1964 Kennedy half dollar weight 65.4 G

Hello coin universe; I hope Everyone is having a great Friday evening so far. I came across this 1964 half dollar weight 65.4 g + none Magnetic, I never herd about this one before, not sure what this is, since this is pretty Enormous in size. Any idea what this may be, or if these are common?
Your true expertise
advice would be greatly appreciated.
God bless 🙏
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