nothing to worry about :o

Someone used a key that you used and try to recover it... but without evidences of the purchase its not possible i think, so... you are safe

Nah, the person who requests it won't know who owns the key, the owner just gets an e-mail.

Like everyone says nothing to worry about I have had some of those as well.

In the end if you have Steamguard active and if you have a secure email account no one can access your account when trying to recover a Steam key.

You shouldn't worry about that, it has happen to me once or twice before, though i very rarely get unused keys from the forum, which makes me question where have they come across the same key

you are cool mate , you don't have to worry :)

That happens when you click on the "Recover key" or something like that when it shows up as a duplicate. It has no repercussions whatsoever, as far as I'm aware.

What it does is:

1. Identify the account holder of the account the CD-key was used on
2. Send an e-mail to the e-mail associated with that account (in this case: your own) with the following information: Account name

Purpose: In the case you forgot your account name, you could request it to be sent to you by providing a CD-key from a game you redeemed on that account in the past. (In other words, if you forgot which account you redeemed the key on, this is the solution.)
Since others don't have access to your e-mail, they won't obtain any information either.
This works similarly to the usual 'Forgot your username?' options known from other services.

I'm not informed enough to answer to your question,but i love your new upgraded picture,did you do it yourself?It is amazing,it's simple but beautiful,you even added a shadow effect,I am impresses sir.