Either they re-used a back prepared for the previous batch, two years before on the line, or they mistakenly used a 1961 stamp in 1963.
- If your guitar is an acoustic, please read this and tell everyone about it : ALL Harmony acoustics were made from solid woods, even the lowest of the lower grade student model, made from solid birch.
Its very weird and I'm wondering if there was ever any rumors of misprints in the serial numbers. - Yes, it's definitely not rare to see "misprints" serial stamps inside Harmony guitars, between similar models.
They were made on the same assembly line at the factory, and of course the body was the same before routing the holes.
In the Harmony world, the interested buyer is often rarer than the guitar itself.
- Usually you will find two stamps inside your Harmony guitar.