It depends on your needs. If you want to see that you VB program sends and receives on the COM port then you may use any serial port monitor (Advanced Serial Port Monitor for example).
Otherwise you may use the following program. It may split one COM port to two new virtual COM ports.
actually i need to make a controlled home automation...i designed my VB app
and run my proteus simulation on same port and got error cant acces serial ports simultaneously in VB. but worked fine when VB is configured to COM1 and proteus to COM2 and joined them with virtual serial software.....
Then how will i connect my MCU to COM1 and run VB at same port??