Can two people use the same turbo tax on the same computer?

If you are using the desktop version of TurboTax, yes you can. You can file up to 5 federal returns using the desktop version. If you are using the online version of TurboTax, then you will need a TurboTax account for each person that you are preparing a return for because only one tax return can be filed per TurboTax online account. 

In the license it states "C. Additional Restrictions. You are not licensed or permitted under this Agreement to do any of the following: (1) allow any other person to use the Software;" What does that mean? Even on the same  computer ?

That means you cannot give it to someone else to load onto another computer for their separate use.