Unfortunately there is no command to change the id permanently. The supported mechanism to formally change the shelf id is to set the id physically on the shelf, then power-cycle the shelf.
Having shelves with the same id is not an functional problem. If two shelves have the same ids but are on different loops, they are still unique to the controllers and there is no error condition indicated. If the two shelves are on the same disk loop, one of them will get "soft assigned" an id above 100 by the controllers to make it be unique, and a warning/error indication on the shelf and controllers will be listed so that it can be corrected.
Of course, visual identification of a shelf or a disk within a shelf is more challenging with two shelves having the same id, say when replacing a disk. Definitely can create an administrative/operational type of issue if maintenance activities take place on the wrong shelf.
Hope this helps.
Senior Systems Engineer | cStor
NCIE SAN Clustered, Data Protection
Kudos and accepted solutions are always appreciated.