I don't think so. If the math contest is national, it will be clearly written that it is a national math contest, and what is not written is held by colleges and universities themselves.

Supplementary information:

In 2009, the first China Mathematics Competition (CMC) was held. As a national high-level discipline competition for undergraduates, CMC provides a stage for young students to display their basic mathematical skills and mathematical thinking, and accumulates research materials for discovering and selecting outstanding mathematical talents and further promoting the reform and development of mathematics curriculum construction in colleges and universities. Sponsored by the Chinese Mathematical Society, it is also a good relay of the national high school mathematics competition in colleges and universities.