New builds belonging to Windows 10 for phones and Windows Phone 8.1 GDR 2/ Update 2 have surfaced on the WP Bench site.
Build 8.10.15113.0 for Windows Phone 8.1 GDR2 in the WP Bench seems to be slightly older than the one that appeared through leaked screenshots posted by Chinese site ITHomes. Their sources assert that Microsoft might skip GDR2, at least for the preview users.
Apart from GDR2, there are two new builds of Windows 10 for phones which showed up in the benchmark site. The first one, 10.0.19648.05 is more advanced than Windows 10 technical preview for phones, 9941.12498, which Microsoft seeded for Windows Insiders.
The other one, 10.20.9648.05 appears to be the same as its last six digits matches with the build 10.0.19648.05, reports NokiaPowerUser.
Windows 10 technical preview for phones build 9941.12498 could be followed by builds named 10.0.xxx, or according to the current naming status the last five digits of the build might match and the future builds could be something like 9xxx.19648.
Windows 10 technical preview for other Lumia devices
The first technical preview build for phones supports a few devices such as Lumia 630, 635, 636, 638, 730 and 830, and more phones will be phased in with each new preview build. The names of the additional devices will be announced when the build comes out.
Meanwhile, Joe Belfiore has already announced that Microsoft is working on other devices and one among them is the Lumia 1520.