I tried all morning to get the bug to trigger for both the white shirt and white pants at the same time. I was able to pull it off once, but didn't write down the steps that I took. I couldn't recreate it after that, either.
Here's the sequence to get the bug to trigger for one article, though:
1)Dirty white shirt and dirty green skirt go into the wash together. Orange shorts go in the refresher. Press next.
2)Add white shirt to the drying rack. The sprite for the clothing hanging on the drying rack is green. Press next.
3)Give white shirt to Bertrude. It shows that the shirt in her possession is green and is marked as incorrect.