We had a 1993 Burley Duet with a nutted axle, and a freewheel. The axle broke. Replaced with a QR hub with a freehub, cassette.
The replacement is still going strong 15 years later.
Modern Tandem hubs with QR are stronger than what came on your Burley, in part because the placing of the bearings on hubs using cassettes as oppossed to frewheels.
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You could fall off a cliff and die.
You could get lost and die.
You could hit a tree and die.
OR YOU COULD STAY HOME AND FALL OFF THE COUCH AND DIE.