Code redeeming fraud?

[Usagi]

I have just been trying to redeem some code cards from pre-release kits. I have had 4 in a row now tell me they have already been redeemed. these are codes that went straight from the package to trying to redeem them, so they have no been legitimately redeemed in any way.

This is after the first 4 redeemed properly. Is there some kind of limit to redemption on these? or have these codes been somehow stolen through some sort of hack? Has anyone else had a problem with this?

[Traumaturgy]

On some code selling site i saw that there are limits of codes per mtga account. It depends on expansion, but generally the newest ones have 5 pre-release codes (each one is 6 boosters), and 5 promo pack codes (one booster each), which translates to 35 boosters total. For older expansions its 1 pre and 5 promo codes respectively, so 11 boosters. Everything beyond limit- you cant redeem. So maybe try them on another account, or sell/give away.