I pulled the same stunt and forgot, the brown one is the fuel resistant material one so I'd put it in first. In my case I had extra brown so just used two of those. Make sure you use that spacer (goes in between the rings), it's necessary for o-ring crush. When assembled and car tested wiggle the connector around while looking for leak.
Thanks amc49, I ended up figuring out that the first one is brown o-ring, then the white washer, and then the yellow o-ring. I took pics with my good camera and was able to zoom in enough to see the order before I pulled them out. It's all back together and runs great. Thanks again for responding.
You gotta wonder why they change the color. I'm thinking the cheap suckers they are, need one only to seal, the other is much cheaper bought in bulk and used as a spacer only. But why engineered to require two to begin with??? Maybe they weren't sure at final design time that one would not leak.............the difference in price could easily make some assembly guy a bonus when he saves the company $10K on simple o-rings. Like using two bolts on each end of bumper instead of the four that brackets are made for, they do that stuff all the time.