You have one iPhone 6 black and one white. You want to swap the colours and you will end up with one black and one white.
There is something here I'm not getting. Are you trying to change the colours to seem like the IMEI matches the colours you want for some reason?
I admit I'm confused.
Personally I wouldn't try anything like this. We often get question from folks who engage in repairs and run into trouble.
Other choice is to take it to a proper Apple repair shop.
Sent from my SEXY GORGEOUS AWESOME GOLD 128G iPhone 6

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