How to identify Copied Opportunity

Summary: How to Identify if the Opportunity is copied or if the opportunity is created from Create Opportunity button.

In Oracle Support we have found document Doc ID 2246001.1. As per document we have tried but this code is not working.

Our requirement is, if the opportunity is copied then we want to set a check box field checked and if the opportunity is created from UI Create Opportunity button, then check box should not be checked.

With below code it is not working as expected.

if(OptyId.toString().equals(CopyOptyId_c)){

 setAttribute('OpptyCopied_c','N')

 println("if N")

}

else

{

 setAttribute('OpptyCopied_c','Y')