Silktouch Duplication Bug

Device:
Xiaomi Redmi Note 4X

I was playing on my Realms though, I mined a furnace with Silktouch Pickaxe and it drops 2 instead of 1.

Steps to reproduce:
1. Obtain a Silktouch Enchanted Pickaxe
2. Obtain a Furnace and place it
3. Destroy the Furnace

Video:
https://youtu.be/lxcoaOoUFPs