Two riddles to ponder on

Pronounced as one letter,
And written with three,
Two letters there are,
And two only in me.
I'm double, I'm single,
I'm black, blue, and gray,
I'm read from both ends,
And the same either way.
What am I?

There is a green house,
inside the green house is a white house,
inside the white house is a red house,
inside the red house is a bunch of black babies.
What am I?