First thought: Are tires the same size? Are the wheels the same? Sounds dumb, but had that problem with mix-and-match wheels on a util. trailer.
Then: measure the distance from backing plates to spring perches on both sides.
Then: check if the box is centered on the frame.

I suppose if the axle slipped back on the leaf spring on one side, it could rub on one side.

Current fleet (subject to change w/o notice)
\'49 GMC 3/4-Ton , 60 Austin Healey Frog-eye Sprite (some assembly required), 2011 Dodge Avenger, 2015 Jeep Cherokee. No, they don't all run.
My other ride is a (B737)no, (B767)no, A320.... Update... was Embraer E190, now Boeing B787.

Knowledge is a wonderful thing, but ignorance means you don't know you can't do something.