Attacks » Signs of Evolution
Can I use "Signs of Evolution" to get a Vaporeon and a Glaceon from my deck?
No, you may not. Vaporeon & Glaceon are both Water types, and the three Pokemon retrieved by Signs of Evolution must all be different types.
Source: Plasma Freeze FAQ (2013-05-16), TPCi Rules Team (2013-05-16)
Attacks » Signs of Evolution
Can I use "Signs of Evolution" to get two of the same cards that evolve from Eevee if I don't have 3 different ones in my deck?
No. Each one you take out of your deck must be a differently typed evolution of Eevee; you may not retrieve more than one Pokemon of the same type.
Source: Plasma Freeze FAQ (2013-05-16), TPCi Rules Team (2013-05-16)