10 Kennedy bonds?? Are these bonds from the Kennedy era? In that case, I suspect that the bonds in questions are fakes.. we are past the usual 30 year mark for redemption.
If you can’t fake the government’s currency, fake their treasuries.. Many of the new security measures have made counterfeiting US currency harder. It also makes me wonder if this has been going on for a few years on a large scale(counterfeiting against US currency). That could explain the push to modernize the US currency.
Since the treasuries have serial numbers, it shouldn’t be too hard to determine their authenticity. I suspect that most large denomination notes are tracked individually.