Funny Continuity Error

So I noticed this while rewatching.

We know that in the episode we meet Sheriff Murphy, Sheriff Murphy was the first Murphy of Murphy's Law in 1875, but when you watch the Murphy Family Vacation Episode, the episode claims there was Murphys that caused the Chicago Fire with their Murphy's Law which took place in 1871.

https://milomurphyslaw.fandom.com/wiki/Murphy_Family