@harklrd asked: "Can I file more than one return with turbotax deluxe online?"
I assume you are asking about a Federal return. If so, the answer is "No". You can prepare 1 Federal return per online account per year. If you need to file another Federal return for someone else, you have to use a different online account (User ID) for that person. Each account needs its own User ID. In the account profile section, however, you can use the same email address on up to 5 accounts for notification purposes, but each User ID must be distinct.
NOTE: If you try to prepare more than 1 Federal return in the same account, it would overwrite the first return
Addendum:
If you have multiple returns to prepare, you may wish to consider a desktop product to install on your computer. In the desktop products you can prepare as many Federal returns as needed, but are limited to 5 free Federal efiles (IRS limit). Additional returns over 5 can be printed and mailed.
Yes, you can also file multiple return with the Online version of TurboTax.