This question gets asked on here at least twice every week. As soon as the search function starts working again, do a search. In fact, just a few posts down below yours someone else asked the same question. Here is their thread:
http://www.disboards.com/showthread.php?t=3066531
CheshireFigment is a ticket CM that posts here on the DIS. He has a comprehensive sticky that tells you anything you could ever possibly want to know about tickets. Because people are always asking about doing exactly what you are wanting to, he included the following explanation about base tickers vs hopping:
Frequently Asked Questions
--------------------------------------------------------------------------------
Here are a few of the most commonly asked questions about tickets and expanded answers for them.
A(1). I have a base ticket for eight days, although I will only be spending six days in the Parks. The day I have for Animal Kingdom I also have a dinner reservation at Epcot. May I use one of my extra days for evening admission to Epcot?
A base ticket is one major (theme) park per day. You are allowed to re-enter the same park if you leave it on one day, but it can only be used at the one park.
Note that the ticket may state on it either "Not Valid For Park Hopping" or "One Theme Park Per Day". That should be a hint.
If you put the ticket in the turnstile of another park the display on the Guest side of the turnstile will be "ACCESS DENIED". The top line of the display on the Greeter side will give information about the ticket, and the second line of the display will say "CROSSOVER NOT PERMITTED". The turnstile will not unlock.
This is because Disney charges $10.00 per day over five days on an adult ticket, but charges $57.00 to allow hopping. ($35.00 on a one-day ticket.) It does not make economic sense for Disney to allow this.
If you actually have multiple tickets (more than one physical ticket per person) as opposed to multiple day tickets, you can use these tickets for multiple entries. But it makes absolutely no economic sense as a separate ticket costs a lot more than adding hopping to a ticket.