Legal analysis: Generally speaking, a bid document is valid only if it is stamped on the bid letter or the cover of the bid document, and does not need to be stamped in multiple places. Some bidders believe that only content stamped with the official seal of the bidder is valid, which misunderstands the role and purpose of the seal. Some tenderers require bidders to affix the official seal of the bidder's unit on business licenses and other certification documents issued by third parties, which is even more unnecessary. Of course, in order to facilitate the review, the tenderer may stipulate the location of the seal or signature of the tender document.

Legal basis: "Tendering and Bidding Law of the People's Republic of China" Article 9 If a bidding project requires project approval procedures in accordance with relevant national regulations, the approval procedures must be completed first and approval is obtained. The tenderer shall have the corresponding funds for the bidding project or the sources of funds have been confirmed, and shall truthfully state this in the bidding documents.