I have two USB devices and both require usbserial to be loaded in order to access them. However, One of the devices, a USB GPRS modem requires that it be loaded like this:
modprobe usbserial vendor=0x1410 product=0x4400
while the other one loads just fine like this:
modprobe usbserial
Is it possible then for me to use both of these devices at the same time? What's the purpose of those additional vendor and product arguments?
If your second device is autodetected correctly as a usbserial device when connected (like most serial adapters do), then it should be OK : using a vendor and product id won't prevent usbserial to detect your second device.
These two parameters are used to tell the driver to use the device on the usb bus identified by these informations as a serial adapter. Usually drivers scan the bus (PCI, USB or other) for supported devices, but in this particular cases there probably are too much devices to identify them all in the module :)