There is no duplication.
Squeezeebox devices are not natively DLNA compliant. MC and other DLNA servers/devices cannot see them and they cannot see or use DLNA servers. But Whitebear and the latest LMS are able to make the squeezebox devices appear as DLNA devices and the LMS server appear as a DLNA one. If you use Whitebear you should disable the built in LMS DLNA plugin, but neither is perfect. The LMS plugin provides a pretty crude, immature DLNA server that does not work with all DLNA clients (it crashes my iOS client).
On the other hand Squeezebox's proprietary protocols, like Sonos, are better at some things than DLNA. One of the things is syncing of several players. Squeezeboxes can sync near-perfectly, so without any tweaking the same sound is coming out of all at the same time. You can even use one for the left channel and another for the right. DLNA needs manual tweaking to try to emulate the former and it is never as good (there can be drift over time or from moment to moment). Right now I still mostly use the Squeezeboxes and LMS to play music. I even load up the Squeezeplay client on the PC if I want to sync music between a PC and other Squeezeboxes in the house, as the sync (although not quite perfect) is better than I have been able to achieve with DLNA. But of course, you may not be bothered about syncing at all!
