The yet to be announced Nokia Lumia 530 showed up at Vietnamese web shop Mainguyen. The store previously listed the Samsung Galaxy Core 2 Duos and Galaxy Pocket 2 before they were announced and the specs proved very accurate.
If the new Nokia Lumia 530 specs are to be believed, the phone will be a fairly minor upgrade over the current Lumia 520. The screen is still 4" big but with 480 x 854 resolution, a minor change from 480 x 800 to bring it to 16:9 aspect ratio. This one will have ClearBlack tech though, which might make a big difference in sunlight legibility.
The chipset has been moved to a Snapdragon 200 with a quad-core 1.2GHz processor, presumably Cortex-A7 but could be an A5 too. In either case we're not sure it's much of an upgrade over a dual-core Krait. The built-in storage has been cut in half (4GB) and the RAM is still at 512MB.
The Nokia Lumia 530 will reportedly the same 5MP / 720p camera as its predecessor and the same 1,430mAh battery. A compass has been added to the limited sensor array of the Lumia 520, but on the downside the phone grew thicker - 11.7mm, up from 9.9mm.
The specs of the site confirm the 530 is a dual-SIM device (the FCC already certified it). It will be available in Grey, White, Orange and Green. The image on the product page shows a blue phone, so it's either a placeholder image or there's one more color option.
Keep in mind those specs might be wrong, previously we were seeing rumors of a 4.3" screen. However the dimensions from the FCC match with those of Mainguyen - 119.7 x 62.3mm, practically the same as the Lumia 520 so chances of a bigger screen are slim.