Steam key duplicated?

First of all i alredy opened a ticket, waited for a week and i still havent got an answer

i used to play rust on the web browser, once it made the switch to steam i got my steam key, But when i tried to activate it on steam it printed it was alredy used / duplicated, no one else has access to my account neither the key so i cant understand why its used alredy…

The only thing you can really do is file a ticket.