If the Toshiba shows up in Disk Utility, you should be able to erase it. What is the error message you get when you try an erase? Make sure you are not trying to erase your OSX installation because it is mounted and such an operation will fail.
A Disk Utility screen shot may also help. If not possible, can you provide the output of diskutil list from the OSX terminal with the Toshiba connected? Please remove any personal information like serial numbers, etc.
Likely where that second "Drive" came from, but may be gone now...
In Finder's Menu, select Go menu>Go to Folder, and go to "/volumes". (no quotes)
Volumes is where an alias to your hard drive ("/" at boot) is placed at startup, and where all the "mount points" for auxiliary drives are created for you to access them. This folder is normally hidden from view.
Drives with an extra 1 on the end have a side-effect of mounting a drive with the same name as the system already think exists. Try trashing the duplicates with a 1 or 2 if there are no real files in them, and reboot.
If it does contain data...