You want to copy the watchers and the reporter from the original issue when developers close an issue with a resolution duplicate.
Solution
Write the code
Enter the following SIL™ code.
string u;
number n=0;
n=size(fieldHistory(key, "Link"));
if (n>0 and resolution=="Duplicate")
{
string dKey=getElement(fieldHistory(key, "Link"),n - 1); // history
%dKey%.watchers=addElementIfNotExist(%dKey%.watchers, reporter);
for (u in watchers)
{
%dKey%.watchers=addElementIfNotExist(%dKey%.watchers, u);
}
}
Next, add this code to the action on the Resolve issue transition.