steam product key duplicate product code error

Games Halo: The Master Chief Collection
1

for the MCC’s Season 8 Flight I was trying to put the code into steam and I am getting a duplicate product code error when attempting to register the key.

2

The flight ended a few days ago and all steams codes get revoked at the end of each flight

3

> 2533274813317074;2:
> The flight ended a few days ago and all steams codes get revoked at the end of each flight

pain.