In the episode where Raymond comes back from Italy, his parents drive their car through his house. When their wall gets fixed, Ray's wife said they had to get a different kind of wallpaper, because they didn't make the same kind as they had. But, if you look closely, you can see that the wallpaper is the same as part that didn't get driven through.
If you saw the episode, you would know that when Raymond is complaining, Debra says: "You can't even see it 3 feet away". We never get any close picture of it so......well..we'll never know!!!
Most of the plot on that episode is the fact that the wallpaper looks ALMOST the same, and only Ray thinks it's completely different. You wouldn't be able to notice if the lines in the paper were slightly thinner (which is what was different).