It's the first time I opened this chest.
Nothing is added to the inventory.
Actually, if you looked at your ITEMs you would see a glitch in the item window, that is from the 'invisible' item. Apparently for what ever reason the Death Necklace isn't being loaded in to the item array. or the index is wrong. You can sell the blank item for 0gp too!
I also noted there are some differences between DW64 and Nes with tiles/backgrounds.
It reminds me DW2 from NES.
Some musics in your game are in stereo.
Is NES a stereo system?
The tiles and sprites are what I saw playing the game on the original NES console.(image below) Which I believe is different from the Japanese(and perhaps other regions) version of the game, which were simpler. For whatever reason.
As for audio, its a clone not an emulator. So all the audio is recorded 2 channel, 16bit, 44100hz. I believe the original hardware was Mono 8bit, at something like 11025hz(or less?).