Well, the whole thing started yesterday (external source) with the appearance of one Nokia Lumia 910 in the list of discoverable devices via Bluetooth during a regular session with the RDA tool.
Oh and by the way, the Remote Device Access (RDA) is a service that allows developers to test their mobile applications and services remotely on various Nokia devices via a regular browser. Devs can remotely control a device, install and run applications on it, or transfer files.
In one of these test sessions later on, another device popped up - the Nokia Lumia 1001. Now that's a serious model name jump and this might suggest it's either a Windows Phone 8 device, or even a tablet.
As things heated up and the interest for the RDA tool grew immensely, people who logged in started finding all sorts of unannounced devices this way. Enter the Nokia Lumia 920, the Lumia 950, the Nokia 510, and the Nokia Belle 805.
Now take all these with a "pinch of salt". Given the hype surrounding the RDA tool since yesterday, it might as well be a case of other devs messing with the available test units to display fake Bluetooth IDs. So for now consider this as just a heads-up. We won't go as far as analyzing the model names and potential market positioning, as they might turn out bogus.