The following two images have been posted on Facebook by Jan, who has found this set for sale, marked up as the SDCC Droid Set. The location is unclear from the image, but based on what we can see the latest suggestion is that this is an image from a Hong Kong Toys R Us
The 3 pack appears to be 6 inch scale looking at the sculpts and contains...
R2-A3, an R2 series astromech droid used aboard Wedge Antilles' T-65 X-wing starfighter
R5-K6 , an R5-series astromech droid that was built by Industrial Automaton and belonged to Garven Dreis, the leader of the Rebel Alliance's Red Squadron (A New Hope)
R2-F2, is the interesting one as he is listed on this box as being the R2 unit who flew with Biggs at the Battle of Yavin. In fact Biggs droid was R2-Q2, and R2-F2 was only added to the Star Wars Universe via the X-Wing Miniatures game.
They all seem to be based on the original wave 1 R2-D2 mould, with new R5 head for K6. There seems to be plug in accessories down the side of each droid.
No more details at this stage, but this looks pretty good as an exclusive pack in terms of content. Considering their place in the Star Wars timeline (circa A New Hope, Rebels Red Squadron) who knows if these droids may be referenced or even appear in Rogue One, or associated media like comics or novels.?
We know from Hasbro Q+A that there will be two Convention Exclusives this year. One will be Rogue One based. And one will be shared between SDCC and Celebration London.
We await more details... and of course confirmation - this may end up being a fake or custom?