I figured My Disney Experience is having issues reconciling reservation information, but today I decided to call to confirm.
My resort reservation email and invoice from the Walt Disney Travel Company are correct with my package, dates, and guests.
But when signing into My Disney Experience, the web site doesn't have the guests listed correctly. For mine, it lists myself once, and then my wife twice, once as a adult and once a child. My child's name is not listed as the child guest.
I called WDW and the CM acknowledged the new site is having issues with the guest listing. She used her internal system to confirm all the reservation details, which were still correct.