Hey there, Chelsea! Adding days to a
Walt Disney World vacation is my favorite thing to do! I am so excited that your dreams of an extra day in the magic are coming true before your trip even begins. Hot dog!
To answer your question, you can purchase a single-day ticket without affecting your other ticket. Since single tickets require selecting a theme park, the system should register the single-day ticket rather than the multi-day when you scan Mickey Mouse at the ticket gate. I say "should" cautiously. It should, but I would call and speak with a Cast Member at the
Tickets line to buy the ticket and make sure it is set up to be the one chosen that day.
Before you do that, I have another recommendation: add a third day to your existing ticket. A Cast Member can tell you the difference in pricing, but a 3-day Park Hopper might be cheaper than a 2-day Park Hopper and a single-day one-park-per-day ticket.
According to the pricing on the website (noting these numbers do not include tax and pricing is always subject to change), a 2-day Park Hopper is $388.54 for the dates of your trip. A single ticket for January 12 currently ranges from $149 for
Animal Kingdom and $169 for
Magic Kingdom. If you plan on Animal Kingdom that day, two tickets would cost $537.54. The Magic Kingdom would be $557.54 for the two tickets. A 3-day Park Hopper would cost $533.07. You might save money and be able to bounce like Tigger between theme parks all three days. Hakuna Matata! My math is based on current pricing, so your costs and savings might differ, but I would call Existing Tickets and ask the cost to add a day before buying a second ticket.
In addition to the Park Hopping benefit, you could also buy any
Lightning Lane passes at the same time, making planning convenient.
Chelsea, I hope this helps–and maybe even saves you some money. My "Disney Math" would afford me Mickey ice cream bars several times on the trip and perhaps even a new pair of Minnie ears, no matter what the difference in ticket cost turns out to be. (This may be good evidence of the need to ask a professional.)
If you have any other questions about any of your Disney vacations, know you have a friend in
planDisney!
See 'Ya Real Soon!
Jana