Hello,
It was possible to save both chips.
They have both the size of 8 MiB.
But they are different images regard to the ckecksum.
If one chip is a 4 MiB part and the other is a 8 MiB part, but you have read two 8 MiB chips, your chip enable pins are not driven properly (both chips end up being enabled at once) and what you read is very likely to be invalid data.
To prevent that, you would want to put a resistor between pin 1 and pin 8 on the inactive chip. The voltage on said pin 1 should then be 3.3 V, which would disable that chip. To connect this resistor, you can use a spare flash chip clip without a programmer.
Best regards,
Angel Pons