Corrections! "Did TEVA really make a better version, or just change the colour?" What has this anything to do with "obviousness" ?
"TEVA told the FDA that the product was the same wrt safety and efficacy. " yes. What has this anything to do with "obviousness" ? This is evidence for inequitable conduct.
IMHO Obviousness would be possible 1) If 1974 patent had some clues that lower molecular weight of cope-1 is more safe. OR 2) If other prior art on cope-1 mentions that changes in molecular weight leads to changes in toxicity , so as to make TEVA's findings obvious