The Gudgeon Family

[Gielreta]

No: HPFGUIDX 106051

It seems likely that there is a thread on this already, but the 
search turned up no matches.  Has anyone noticed that Lockhart's 
biggest fan, one Gladys Gudgeon, bears the same, rather unusual name 
as the boy who taunted the Whomping Willow, Davey Gudgeon?  It seems 
that the two must have some connection.  Why else would JKR use the 
same surname twice?

I looked up Gudgeon in the dictionary, and found that it can be the 
pivot around which a wheel turns, a small fish, an easily tricked 
person, or something easily obtained without skill or merit.  
Shakespeare uses it in the last sense.  Any thoughts?

Gielreta