Yes the duplicate Share name for an external USB hard drive has been discussed in the past. First thing is to ensure your My Cloud firmware is up to date. Second, for some performing a 40 second reset using the reset button on the back of the My Cloud fixes certain issues.
The solution for some with the duplicate USB Share name is to remove/eject the USB drive from the My Cloud using the My Cloud Dashboard USB icon. Then access the Share page within the Dashboard and remove all other Shares that were generated with the USB drive name that have the _x extension. Then reattach the USB drive to the My Cloud and rename the USB Share back to it’s initial name minus the _x extension.
Some pass discussion on the duplicate USB name issue:
https://community.wd.com/t/usb-path-not-found-400044/162239
https://community.wd.com/t/my-safepoints-disappear/160698
https://community.wd.com/t/new-release-firmware-release-04-04-02-105-1-27-2016/148441/68
https://community.wd.com/t/mycloud-creating-numerous-aliases-for-same-drive/160161
https://community.wd.com/t/usb-drive-makes-new-name/152675
https://community.wd.com/t/dublicate-shares-after-reboot/153348
