Your wife things she took another Ambien pill because she did not remember taking the first is she in any kind of danger?

There should not be any immediate danger, however signs of ambien overdose are very serious, if you are worried just check from time to time to make sure she is breathing normal. HOWEVER 10mg of Ambien (two normal dose pills) should not result in these serious symptoms other than extreme tiredness.

On a side note, it is normal with medications like Ambien to forget that you took one and take more and more and more, your wife should create a system where she leaves some indication for herself that she took a dose.

Hope this helps!