I sometimes have stool be 2 different colors: 1) greenish brown 2) white or pale colored. the two colors are swirled together in each stool or one is all green/brown or pale. i have autoim. gastritis, pernicious + iron anemia. what could cause this?

Stuff you are eating at different times is likely mixing to together to do this. Get pictures and share.

In addition to Dr. G's answer I might add that if you're taking iron supplements your stool color may be blackish or greenish. White stools occur with absence of bile salts in the intestinal tract as seen in liver disease or stones in the biliary tree. I recommend consulting a gastroenterologist for evaluation & advice. Any appropriate testing will be done.