I'm by no means an expert, but given that the second test confirmed the result in question from the first, I would be inclined to accept the answer as valid, unless both tests/testers are known to have a high rate of mistakes, in which case you may wish to re-test.
In terms of the intriguing result, it's possible that what you think you know about your family's history and the genetic results are both true.
Your family may well have emigrated where and when you think, but further back in mistier parts of your family tree, your ancestors had to have immigrated to the place your family would later emigrate from, and sometimes our more adventurous ancestors did so from very far afield indeed.
[Prof. Brian Sykes, Seven Daughters of Eve] reports identifying unmistakably Polynesian DNA in an Edinburgh
schoolteacher, Korean DNA signatures in Norwegian fishermen and
African DNA in a white dairy farmer in rural England. Two fishermen on
a remote Scottish island turned out to share Siberian ancestry — but
one by way of Finland, the other via Brazil.