The Bug:

If You rename with anvil Shulker Box (Like renaming any other item), place it and broke it in Creative Mode the Shukler Box will be broken (Removed), but will drop "Copy" (Duplicate) with all the Items inside, the custom name, ect.

How to Reproduce:

1. Rename Shulker Box to any name you want and put some Itmes inside (If you want);
2. Place it on the ground and open it to make sure it's renamed and your Items are inside;
3. Break that Shulker Box in Creative mode - It is removed (Broken), but it drops itself (Duplicate);

• Works with any color / Even crafted, renamed, placed in Survival, Then broken in Creative Mode;