At this point the lack of a Dual Camera for the M9 seems certain since the back of cases has a single large cutout for the lens and flash arrangement.
Since this has been discussed in several earlier leaks we can safely assume that the M9 will arrive with a conventional camera this time around.
Case manufacturers have turned out to be a sort of reliable source of info on future smartphones as Amazon is currently flooded with optional protection for the M9, an HTC flagship which has yet to be announced.
So, we are certain about the back of the device, but some manufacturers seem to have missed the new speakers design as some of the cases still have the M8 grille placement in the renders instead of on the thin slits towards the edges. But it is unlikely that they have produced the wrong case, it seems more likely that the companies have chosen the safe side and stuck with an official image of the M8 in order to avoid breaking confidentiality agreements and revealing something they shouldn’t ahead of the announcement and launch.