There is no point in taking 316 (or 315) after taking 306 (or 305). The content does not vary, just the language, and trust me, there isn't that much of a difference still. If you take 316 then take 306, the latter will not go towards your certifications.
If you follow what MS outlines (take 1 of the following, take 2 of the following), that will determine what is counted and what is not.
Again, I would highly suggest against this. You can mix & match the languages because the certification isn't based around the languages, just the skills necessary for .NET development/architecture design.
Matt Hawley, MCAD .NET
http://www.eworldui.net
Is it permitted to take 306 (VB.NET apps) one week, and then take 316
(C# apps) the following week? (irrespective of whether you pass exam
306)
Secondly, can you choose which exams constitute your MCSD, or is it
done automatically based on the order you take your exams?
The reasoning behind this is that I was thinking of taking the C# MCSD
route, but if I'm studying for 316 I may as well do the corresponding
VB.NET exam a week/few days before as a warm-up exercise. Hopefully I
should pass both, but get the better mark in the C# exam. It will also
keep the HR dept happy if going for any roles involving VB.NET. I
realise of course there is virtually no difference between the two
exams. Similarly for 305/315. Other than the additional expense, would
there be any problems doing this?