Apple (AAPL) is using two different-sized A9 chips in its iPhone 6s/6s+ smartphones, one manufactured by Samsung and another by Taiwan Semiconductor Manufacturing (TSMC), according to a Chipworks report followed up by Ars Technica.

Word surfaced as early as last February that Apple had enlisted bitter rival Samsung solely to make the much speedier A9 chip to power its iPhone 6s/6s+, apparently favoring the Korean manufacturer’s 14 nanometer technology–which enables it to cram more processing power into a smaller area while eating up less power–over TSMC’s 20-nanometer process.

Subsequent rumors ahead of Apple’s September iPhone 6s/6s+ launch, however, indicated the vendor would dual-source the A9 and A9X chipset, with Samsung producing the former and TSMC the latter. The chatter, as Chipworks reported, said the A9 would be slotted for the iPhone 6s/6s+ and the A9X for the iPad Pro, which, if true, would grant Samsung a significant advantage in chip production volume over TSMC for the A9 series.

But the reality has turned out to be much different, according to Chipworks. Lifting the hood on the iPhone 6s, Chipworks found two different application processors in two identical handsets, with a different die size for the APL0898 made by Samsung when compared to the APL1022 manufactured by TSMC. Samsung’s A9 chip, the report said, is slightly smaller than TSMC’s.

The implication of Apple’s A9 dual sourcing, as Chipworks suggested, is the vendor experienced sourcing problems with the chip, particularly considering that it launched the iPhone 6s/6s+ with both versions. Apple reportedly relied on Samsung and TSMC for the A9’s predecessor chip, the A8, although the A7 chip deployed in the iPhone and iPad were made solely by the Korean manufacturer.

Ars Technica reported that iFixit’s teardown of the new iPhones showed the smaller Samsung A9 chip in the iPhone 6s and the TSMC edition in the larger-chassis iPhone 6s+ model but conceded that it did not know if all the new units were similarly constituted.