"Dagger Of The Mind"
"Blue Blooded Steele"
Over a decade later, Remington Steele, posing as heir to the title of Duke of Rutherford, uncovered a murder plot to gain the late Duke's estate. Steele and his partner were staying at the ancestral Rutherford estate for that weekend and one thing should have been noticeable to the discerning eye of the Trueniverse audience.
Both the Haversham and Rutherford estates looked exactly the same, inside and out of the mansion.
Here's the easy splainin for such a Zonk:
One of the Duke of Rutherford's relatives mentioned that the estate had been the ancestral home of the Rutherfords. Therefore, there was no way it could have been the home of Sir Roger Haversham a decade earlier. And based on what Sir Roger's butler Tanner said, Sir Roger had been living in his mansion for many many years.
Therefore, I believe Sir Roger had his mansion built to the specifications of the Rutherford mansion's design. Perhaps he had been the Duke's guest on several occasions, accompanying the Lady Astor to some lawn fete or costume ball. Having seen the splendor of the Rutherford mansion, Sir Roger may have decided to have a copy made for himself.
And in that way we would avoid a Zonk.