Galaxy S6 shipping with two different camera sensors - from Sony or Samsung
This situation mimics what the company did with the Note 4 - the version with an Exynos processor of its latest phablet uses a Samsung-made sensor, reported as SLSI_S5K2P2, while the Snapdragon 805 variant is equipped with Sony's IMX240. At the time, it was argued that it's just the software reporting different strings, because of the two separate ISPs (image signal processors), utilized in the different chipsets.
The thing is, though, that Samsung has eschewed Snapdragon for the Galaxy S6 entirely this time around, and only uses its own 64-bit octa-core Exynos 7420 for all models, with no Snapdragon anywhere to be seen. Users from all over the world are reporting either Sony or Samsung camera sensor strings in the XDA thread below, and there doesn't seem to be any production period, model or carrier pattern determining which sensor goes into what handset.
They are seemingly put in at random batches, and Samsung apparently considers them interchangeable, so we wouldn't worry too much whether it's a Sony or a Samung sensor inside, as both the S6 and the S6 edge seem to take some of the best pictures that the mobile industry can currently offer.