nether quartz stairs to yellow wool

in the nether looking for bugs with nether quarts ore i built a portal to leave when i spawned in an ocean far from spawn(in creative mode with keep inventory set to true)i used the /kill command and the nether quarts stair (i only had 1 in my inventory) had turned into a 64 stack of yellow wool

*What I expected to happen was...: to re spawned with all my items
i should have re-spawned with all my items

*What actually happened was...:re spawned with yellow wool
re spawned with 46 yellow wool

Steps to Reproduce:
1. go on creative mode
2. set keep inventory to true
3. go to nether with inventory matching that of figure 2
4. return from nether with a different portal with the same inventory
5. use /kill command
6. will have the inventory of figure 2

i dont know the x y z of the spot i used the /kill command

(failed to reproduce this bug myself)