patduino:
I get one #error or the other, not both.
That implies that the preprocessor is handling the conditionals correctly. Hmmmmm.
Do you have code somewhere else, like in another tab, that might be compiling too?
Nope, the code I posted is everything, single tab. The problem originally occurred in a larger project with multiple tabs, but I like to pare things down to the minimum that still exhibits the issue. Better for the forum I figure too.