how does Winky know Dobby?

[ingachristsuperstar]

No: HPFGUIDX 53454

I had this thought while reading the thread about Dobby's 
motivation to help Harry.

In the top box at the Quiddich World Cup Harry mistakes Winky 
for Dobby, and then Winky says that she knows Dobby and tells 
Harry what he's been up to since he was freed.

I'm wondering (as you may have guessed from the subject line) 
how Winky could possibly know Dobby?

Winky belonged to Mr. Crouch - famed prosecutor of Death 
Eaters.  Dobby belonged to the Malfoys - famed member of You-
Know-Who's inner circle who somehow managed to escape 
Azkaban.

So, are we to think that either of these men payed social calls to 
the other, thus giving their house elves the chance to meet?

maybe we are to assume that - which might explain how Lucius 
escaped Azkaban.  But that does not fit in the least with Crouch's 
character.  So what are the other possibilities?

As far as I can see, they either had mutual friends and went to 
the same parties (but surely Crouch wouldn't have brought 
Winky - she'd have been home taking care of Crouch Jr.) or else 
Dobby used to belong to someone else.  And if so, to whom?

I don't imagine there are house-elf conventions.

-Ing