Well, there were a few editions with slight changes in them.
Here are the one I am aware of by fixing a lot of gp2x
I'll only list the new changes they added.
1. First Edition: Original release.
2. First Edition: Headphone better soldered, resistor manually exchanged, piece of stick cap cut off as
the original cap mostly always prevented pressing to the left or right.
3. First Edition: Some rubber pads removed (and they are now red instead of black) to reduce the
Plasma Effect when pressing stick button
Also: Speakers now have longer cables (yay!) and have some protective coat.
And: They manually cut off some rubber from the DC / USB Plug so that it fits better in.
4. Normal Edition: The coating on the battery contacts is no longer there. The headphone port gets fixated
by some glue, the LED cover is now milky white instead of totally transparent
(some First Editions, though only a minor few, also seem to have this already!)
5. Normal Edition: They put some tape on top of the battery contacts right below the case.
Don't know what for.
That's all I can remember now... so there always had been minor hardware changes