SystemC Simulation

Error: (E115) sc_signal<T> cannot have more than one driver: 
 signal `dut.sig' (sc_signal)
 first driver `dut.p2'  (sc_thread_process)
 second driver `dut.p1' (sc_thread_process)
In file: <removed by verify.pl>
In process: dut.p1 @ 10 ns