STM32F429IG is able to burn code with 1.7 MB program size indicated by Keil.

[MRafa]

STM32F429IG is able to burn code with 1.7 MB program size indicated by Keil for STM32f429IIT6.

How it is possible, or I have wrong interpretation.

For more clarity it attached controller snapshot and keil compilation snapshot.

[Tesla DeLorean]

The parts share a common die, this has 2MB of FLASH on it, lower cost parts have less of it tested as the time on the test equipment is minimized (units/hour improves)