Mixed SQL Server instances with static and dynamic ports
When a SQL Server named instance configured with dynamic port is started, the dynamic port is provided by windows. The dynamic port range is outside the range of well-known static ports, where port 1433 resides. The dynamic port range is between 49152 and 65535, as documented here.

At subsequent startups, the instances reuse the same dynamic port used during previous startups (the port is written in the registry). If the port is found to be in use, SQL Server asks the OS for a new port. This behaviour is documented in this page, in the "Dynamic Port Allocation" section.

To answer your question in a single sentence: the scenario you describe is impossible (in a supported version of Windows with ranges properly configured).