May you are asking how the coverage class implements the write function for two ports, so this will help you:
// Connections
master_m_agent.m_monitor.m_coverage_port.connect(m_monitor_cov.analysis_port_m);
target_m_agent.m_monitor.m_coverage_port.connect(m_monitor_cov.analysis_port_t);
// In the Coverage class
uvm_analysis_imp_m(master_item)analysis_port_m;
uvm_analysis_imp_t(target_item)analysis_port_m;
function write_m;
sample.cov_m();
endfunction
function write_t;
sample.cov_t();
endfunction
Hope your query answered, if not let me know.
-Cheers
Karandeep