Welcome to planDisney Diana!
You certainly will want only one
My Disney Experience account, so it is a good idea to merge them onto your main account so you will be able to see your reservations whether on your home computer or on the app.
The easiest way to do this is to call a friendly Cast Member at
Website Support. They will look up your accounts and get them in order. Have the email addresses associated with your accounts so they can quickly merge them.
Once you have your My Disney Experience account in order, you will find it to be so handy for reviewing your reservations, canceling or changing your plans, and it will also have all the park information you will need including park hours. You can almost see pixie dust while you are using the app!
I hope you get all the technical details worked out so you can focus on planning all the magical final touches for your upcoming Walt Disney World vacation!
Cathy