duplicates drop Stkcd FRAUD year, force
keep if FRAUD==1

Before deleting duplicate observations, I think it is better to make sure the reason of those duplicate values, otherwise, it would lead to serious results.

你有 typo，应该是

是。不好意思打错了。这就改过来。谢谢提醒。

You are correct. That said, in this particular case, given the amount of information available from OP, this answer is the simplest one that precisely does what OP asks for.

Of course I would hope that all posters give a complete and detailed description of their tasks, their attempts, their issues, and all relevant codes and data. But God (and all the old posts on this forum) be my witness - it rarely happens. So nowadays I sometimes don't bother anymore and just answer the question directly.