And now a little bit more credence has been added to those rumours. 9to5Google understands that the two handsets on the way will be called the "One M8 Plus" (which we assume is the Prime) and the "One M8 Advance" (likely the Ace).
The "Plus" is said to be carrying a QHD display, a zippy Qualcomm Snapdragon 805 processor and 3GB of RAM, agreeing with prior claims from the HTC One M8 Prime rumour mill.
But when it comes to the rear camera, the details diverge. The new source says that the "Plus" will lack the M8's Duo Camera, opting for a single 13MP rear camera with optical image stabilisation.
In @evleaks' recent M8 Prime render leak, the Duo Camera was clearly present - might he have got that aspect wrong?
Ace in the hole
The second "One M8 Advance" device, also believed to be a high-ender, will feature the same specs as the Plus but will house itself in a plastic casing, and be primarily aimed at Asian markets.
The mysterious source says that both device will be made available in August or early September - definitely before the iPhone 6, they said.
Perhaps HTC has swapped the names around? Is this the One+ that the standard flagship was once believed to be named, or did someone just recently notice that 8 isn't a prime number?