Hi...If the person simply wanted to transfer the number out, that could be done and he could start a new line with a new number if he still wanted a line on the old carrier. If he were not under contract, there would be no concern about keeping an old account.
Maybe it is a mistake but you appear to be selling the same phone twice. What did you gain in these transactions? If you add the activation fee, cost of the phone, two years of service at $9.99 per month plus the ETF, you may have lost money. If the line you transferred out was a primary line, one of your remaining lines would become the new primary line.