The difference between destressing the second vowel and eliminating it completely isn't exactly very clear cut. At least with a retroflex approximant r as I have, the transition between r and g brings with it a brief neutral vowel. (Who knows what happens for you crazy people with alveolar approximant or trilled or flapped or nonexistent r's. R is far too complicated a sound.)

I will say that when I actually say Oregon I intentionally delay the pronunciation of g to make the vowel more apparent, but in quick conversational speech, I could completely see Oregon and organ ending up with the exact same ultimate phonological production.

The real crazies are the one who make Oregon end in "gone". It seems to be mostly people who have never lived anywhere near Oregon. Like all these native Wisconsinites.