We just reported the size specs of first Dual-Sim Lumia, the Lumia 630 via a leaked product data sheet image. Now, the device has passed certification at FCC and if you will see the size specs revealed in its SAR report, it matches digit to digit to the specs revealed in PDS.
If you remember RM-977 has appeared in both Single-Sim and Dual-Sim avatars in Zauba records. So, possibly in some markets this 3G device will be launched as a Single-Sim while in other markets as Dual-Sim device.
So, we may be looking at 3 devices,