Two serial ports in one pc?

Is it possible to have more than one serial port in a pc? I am in need of two serial ports for my pc. Of course, I already had one card in there with a female connector parallel port. So, I found another card but this one had a male connector parallel port. When I put the second card in the pc, DOS gave me a conflict error “Conflict I/O Error 2F8 3F8 378”. I went into the BIOS and corrected the conflict but then my floppy drive didn’t work. When I would attempt to access the floppy, it was unable to read any disks. When I took the second serial card out of the pc, everything was fine again. Is the serial port like the parallel – I can only have one in a pc at a time?