Crimson Door Duplication glitch

1)I was playing on 20w06a and created a singleplayer world 
2)I started survival without cheats
3)later opened it to LAN and enabled cheats
4)got crimson door from creative
5)then I placed it and switched to survival and placed the door in my inventory too
6)upon breaking it with fist it duplicated ed and dropped 2 then I placed it but 1 remained in my inventory then I tried breaking it again this time it dropped 3 
Regards-
Devansh 
(I'm too excited for the Nether Update)