I'd think that upsampling by an integer ratio (like 2:1) wouldn't degrade it as it's trivial to introduce data that 'holds the place' necessary but doesn't actually change the actual waveform approximation... then again, I only study interpolation from a mathematical background, so I don't know if DAWs have a magical 'fuck the upsamplers' feature. Since you're already working with a discrete approximation of the waveform, and not moving it back to analog and then resampling it at the newer rate, I don't see where you're coming from.
For the record, it is trivial to prove that given any interpolation method one can add as much extraneous information after the fact as desired and not change a thing. This is what I would expect to happen, at least.
Jeff