Dealer having trouble installing new radio

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Update: It's sort of fuzzy and they don't have all the details yet. They told me that the plugged in the old radio and checked the programming and it was totally different from what specs for my vehicle say it should be. Instead of using spec programming on the new radios, then reprogrammed the new ones with the same program that was in the old radios and it all works now.

Any one care to decipher what this might mean?

The service writer promises to share the detailed explanation of what they did once the tech gets it all written up for GM reimbursement.