I'd open a case with ServiceNow, seems a clear bug if it can't handle the same name being used for two different devices in two different contexts.
But doing as @PhilipDAth says will be a faster fix.
We have a discussion on naming conventions with every customer, some already have one, some have nothing at all, but if we're going to be creating/managing it, we insist on a good structure.
Typically we suggest a hierarchical scheme for network names, varies with customer but one way is ...
[business unit ID_]ISO two-letter country code_[city_]site ID
...where site ID is a globally unique identifier, typically a number zero padded for constant width, best to avoid spaces for portability to other systems.
The things in [] are optional.
The details added to the site ID are to make it easier for people to communicate/understand than a simple site ID, especially when there are hundreds of sites in dozens of countries.
The site ID (or other globally unique thing relating to the network name) is added to all device names on that network, giving unique device names within the organization.
