Applying to multiple PhD programs at the same university?

[mathmollusk]

Is it possible to apply to multiple different PhD programs at the same university?

For example, say I wanted to apply to BU's Math PhD, Stats PhD (both of which are offered through the math department), or Biostats PhD (offered through the public health department).

Do schools allow this? Or is the case more that it's "technically allowed" but would look seem to demonstrate lack of focus? Thanks.

[bayessays]

Some schools allow it, but some explicitly don't.  Some might be able to see that you are applying to multiple programs, depending on the application system they use, but you probably won't be able to figure this out. I don't imagine applying to statistics and biostatistics at the same university would look that strange. Math and English literature might raise some eyebrows. At BU, I probably wouldn't apply to both the math and stats programs in the same department since that process is probably more centralized. But if the school allows it, I don't think it would be weird to apply to both stat and biostatistics there. A lot of people have tight geographic constraints, so it makes sense to apply to as many programs in an area as possible.