one 250 GB firewire hard drive shows up on desktop as two 250 GB harddrives...

I had a brand new blank 250 GB seagate hard drive installed in a firewire enclosure.

When the person formated that harddrive somehow he ended up with two hard drive icons on the desktop each being 250 GB.

Can't figure out how that happened and NOW how do we get only one hard drive icon showing up on the desktop with the 250 GB capacity.

I can;t figure out how to use Disk Utility to solve this problem.

Help please, please, please.