Series Ee Bonds Maturity Date Question Regarding EE Bonds?

Question regarding EE Bonds? - series ee bonds maturity date

I need a clarification on the following statement on the Treasury Direct Web site on EE Bonds: "Book Series EE savings bonds sold at half their face value. Guarantees that the new Treasury Department EE Bond twice in 20 years at the time of issue. Does this mean that if you buy a bond paper, your initial investment of at least four times? For example, if I have a loan of $ 100 EA, and spend $ 50 (half their face value) to a value of $ 200 (double the value of duty), the expiration date? Furthermore, why the EE bonds are sold directly to the nominal Treasury and what the trick is to buy paper EE bonds are sold at a discount of 50%? Thanks in advance.