There is another popular Disney forum out there where the info being propagated regarding the January 1 changes imply that they're enforcing the limits on a "meal-period" basis, but neither of the dining CMs here on the DIS who have shared info about the system changes haven't indicated that. What they've indicated is that while credits are now separated for adults and children, and you can no longer get more adult meals than you're entitled to from one visit to the cash register, nor can you get more adult meals than you're entitled to for your entire stay, if you wanted to have two meals during lunchtime, you theoretically still can.