Proof of work, of course. The black one is a copy. Why do you need to copy the original? According to the document, the copy shall be stamped with the official seal in time, and it needs to be stamped with the official seal again. In fact, it is better to go to the financial department to issue a certificate of income and affix a financial seal than the official seal of the unit.

If your organization is a public institution, there are youth league committees, women's federations, trade unions and so on. That chapter will do, as long as you say which department you belong to, especially the chapter of the trade union, because there is a code.