Each DLNA device should have a UDN, a unique device number. Poly's seems to change, these are the various UDNs my poly has had in the last day:
As per the spec Click here to view the UPnP Specifications on page 52:
REQUIRED. Unique Device Name. Universally-unique identifier for the device, whether root or embedded. MUST be the same over time for a specific device instance (i.e., MUST survive reboots). MUST match the field value of the NT header field in device discovery messages. MUST match the prefix of the USN header field in all discovery messages. (Section 1, “Discovery” explains the NT and USN header fields.) MUST begin with “uuid:” followed by a UUID suffix specified by a UPnP vendor. See section 1.1.4, “UUID format and RECOMMENDED generation algorithms” for the MANDATORY UUID format.
The result of this is multiple Poly entries showing up in Glider, as an example: