related to mounting.......

can i mount the same mount point to two different file system......

Nope you can't and you're not advised to try to do so

Yes you can indirectly by using lofs.

How to mount and access to USB on Sun Solaris 9 ?
Thank you

ls -l /dev/dsk/c0 |grep usb
That doesn't (always?) work, because the device might not HAVE "usb" in the name. For example,
/devices/pci@0,0/pci1028,155@1d,7/storage@7/disk@0,0:a
so you can do a iostat -En to identify your usb device, then..
cd /
mount -F pcfs /dev/dsk/c*t*d*s
:c /mnt
cd /mnt <-----usb contents in here