Just curious, as I just found a loose manual which I'll be trading soon. I don't own this game so I can't check the flaps, but I can see that the manual is different while having the exact same code (no -1 added to indicate a change).

1st version: box has thicker black line, manual has thinner black line. See here


2nd version: box has thinner black line, manual has thicker black line. See here


Notice they both look to be the same version except for this detail. There is a reprint with a black ESRB logo and a revision -2 manual. See here
This -2 manual is different and it's easy to see the added reflections where the vertical "GAME BOY" is written.

So I'm wondering if they forgot to add -1 to one of the 2 manuals above, so they jumped to -2 for the reprint? Anybody with a -1 manual?

Oh, just noticed the 1st manual with thin line is Printed in Japan while the one with a thick line is Printed in U.S.A.

I've had both of these variants since they were in stores. At launch all GBC games had that iridescent metallic sheen on the Game Boy Color banner. The GBC box did too. Very soon after they changed it to the graphical version that isn't reflective/metallic-looking. It's kinda funny seeing people sell the wrong box claiming that it was from launch. This happens with so-called "Launch Edition" consoles and handhelds all the time.  

So you mean the one in my 2nd picture is the launch version? This would mean the box/manual were first produced in the US and then in Japan, I find this rather curious if it's the case.