I recently asked a Question on security.stackexchange.com.The question was related to XSS so in my opinion it belonged to the security website.

There was a comment on the question saying that a similar question exists on SO and my question was a duplicate (I think he gave it a down vote). The guy was right but the question was asked on another website (SO). There may be a case when person asking a question might not have an account with the other website.

Is it a good practice to mark questions duplicate if you have seen a similar question on some other website?

I recently asked a question on security.stackexchange.com. The question was related to XSS so in my opinion it belonged to the security website.

There was a comment on the question saying that a similar question exists on SO and my question was a duplicate (I think he gave it a down vote). The guy was right but the question was asked on another website (SO). There may be a case when person asking a question might not have an account with the other website.

Is it a good practice to mark questions duplicate if you have seen a similar question on some other website?

I recently asked a Question on security.stackexchange.com.The question was related to XSS so in my opinion it belonged to the security website.

There was a comment on the question saying that a similar question exists on SO and my question was a duplicate (I think he gave it a down vote). The guy was right but the question was asked on another website (SO). There may be a case when person asking a question might not have an account with the other website.

Is it a good practice to mark questions duplicate if you have seen a similar question on some other website?

I recently asked a Question on security.stackexchange.com.The question was related to XSS so in my opinion it belonged to the security website.

There was a comment on the question saying that a similar question exists on SO and my question was a duplicate (I think he gave it a down vote). The guy was right but the question was asked on another website (SO). There may be a case when person asking a question might not have an account with the other website.

Is it a good practice to mark questions duplicate if you have seen a similar question on some other website?