Rendering glyph outline and normal to matching bitmaps

[Timo Suoranta]

I render glyph twice, first to get bitmap of 'normal' glyph, and second to
get bitmap with outline stroke.
I need to combine these to a single two-channel bitmap.
But the bitmaps have different sizes. How do can I render normal and
outline to matching bitmaps?
Or would it be possible to get such two-channel bitmap directly with
freetype?

Thanks!