How to check the Wallet Code that I redeemed was safe ?

[shana (Bán book, plus + cache)]

Someone bought items from me and paid by wallet code. How can I know that code is safe to accept the offer?

[Cassidy]

You won't know if it's a duplicate until you try to activate it.

[Ogami]

You cant. Trading items against wallet codes or money in general is not allowed by the Steam trading rules. If you get scammed ( which is HIGHLY probable) its 100% your own fault.
Only trade items VS item in ONE trade window or sell items on the market for Steam Wallet credit.
NOTHING ELSE.

[ELF EYES]

cant it a 50/50 on you end if not like how you did it lurn mistake for next time

[wuddih]

https://support.steampowered.com/kb_article.php?ref=3415-WAFH-6433&l=english#whatscams

There are a number of common scams users may attempt to deceive you out of your items:
[...]
Money For Items - A user offers to send you money in the form of PayPal, PaySafeCard, Steam Wallet codes, Steam Digital Gift Cards, etc. The scammer usually sends you a fake payment code after the trade is completed. In the case of Steam Digital Gift Cards, the scammer may even appear to pay you first, but be planning to charge the Digital Gift Card back later or buy the gift card with a fraudulent credit card.

[shana (Bán book, plus + cache)]

I mean, he give me the code to redeem 1st. It works and I receive the wallet exactly. After that, I trade my items to him. But is the code legal ?

[999999999]

Początkowo opublikowane przez shana:

I mean, he give me the code to redeem 1st. It works and I receive the wallet exactly. After that, I trade my items to him. But is the code legal ?

It can always be revoked by the other person by issuing a chargeback.

This is why you don't trade for things that can not be traded within a single trade window.

[ReBoot]

Początkowo opublikowane przez shana:

I mean, he give me the code to redeem 1st. It works and I receive the wallet exactly. After that, I trade my items to him. But is the code legal ?

You can not know. All you can do now is to pray to whatever diety you believe in.