To clone the electronics of the D4, I'm assuming they copy the board trace and then try and work out all the component values and also attempt to dump any custom programming off the chips to mimic the originals operation incl LCD display. They'll clone as close as possible but undoubtedly making a few dodgy calls either on undecipherable component values/programming or just by using rubbish quality parts?
Mine is cloned so well that even the hidden long press low current charging mode for small batteries and nocturnal mode that switches the lcd back light off both work. They've really dived deep to copy the device, the sophistication is quite remarkable, they've basically tried to do a perfect clone, not just in looks but also operation.
The earlier D4 clones(the earlier version with the WORLDWIDE spelt with a C on the box) from all reports were pretty rubbish, they overheated and didn't work very well for their intended use as battery chargers. The current clone(looks like they have been in the market for the last year or so) seems decent enough compared to say crappy Trustfire type chargers.
I should probably just throw it in the bin straight away but I'm probably too damn thrifty for my own good, I've tested mine with some AA and AAA NIMH and my experience thus far is that the charger works as I expect a decent charger to work, the charge time/cell temps and terminating voltage seem within spec. Granted its early days and I'm hesitant to try 18650 cells in it but seems useful for old/junk AA or AAA NIMH with higher internal resistance that are often neigh impossible to charge on home use chargers.