Is the 20 cm Lightning to 30-pin adapter functionally different than the shorter all in one part? Are the two male Lightning to female 30-pin adapters that Apple is selling functionally equivalent (other than the fact that one has a 20 cm cable between the endpoints)?

 Part MD823ZM/A
 Part MD824ZM/A
Yes - they are equivalent in all measurable aspects other than length. Sometimes we find out things that don't make the public specifications about Apple products, but these two items don't seem to fall into that category.