Eames 670/671 Strange configuration  

I have recently purchased an 2nd hand Eames 670/671 in Australia. It has a peculiar configuration.

It has:
Silver circular clips (tells me that it is pre 71..I think)
The edges of the shells have 7 clearly identifiable, consistently sized ply(s)
The cushions fillings are a combination of foam and something else.
All shells and cushions have the number 6886 stamped/pressed

so far so good......I'm thinking that " this just might be a Herman Miller pre 1971 classic!"

But here is where it gets weird:

The two bases are that of a Vitra model. White plastic insertable glides.

So now im thinking: "perhaps this chair is a married"

the final piece to this story is that the chair itself has a silver badge/sticker, not unlike that of the typical Herman miller badge..

EXCEPT: Around the outside of the badge it reads "Herman Miller (Aust.) P/L

Can anyone shed some light on this chair for me?