AFAIK, Nook STR/Glowlight only lets you create shelves and manually select from the current list of books which titles go on them. At least I could find no way to automate the creation/population of shelves.
At least Kobo has sense enough to allow for an automated method that Calibre can handle. It has been working PERFECTLY on my Touch. Multiple shelves, no duplicates, etc. On the Glo only one series has duplicates and it seems I was able to kill one duplicate by deleting the books from the Glo through Calibre, disconnecting, reconnecting and resending -but still was left with another duplicate shelf. I need to try it again and see if I can remove the remaining duplicate that way. Just was too annoyed to think of trying it the first time around. I wanted to read, not debug something I just paid 130 for.
I may be dead wrong, but have the intuition that something in the shelf creation process or data transfer process is causing something to fail, even though a shelf record actually has been created, in such a way that a routine gets run multiple times to create a shelf it thinks was not properly created.
If they can't find the bug, I'd venture a guess that they could at least wise up enough to stick in a routine that goes through and eliminates multiple identical shelf records? Hell, for all I know there may only be one shelf and the display routine might be showing multiples... though I recall someone saying they had manually edited their database and removed multiple records.