If you are getting the same measurement with both powders/reagents, I would continue to use them. I would just use the older ones first.
The 0870 powder will take on a light bluish/lavender hue over time. If that's the color you are seeing, I wouldn't sweat it. If it turns a dark blue/purple, then I would be more concerned. Even then, you can always do a comparison test using the older powder and the newer powder. If you get the same results, you can continue using the older powder with confidence.