Associative array dup property?

[Adrian Matoga]

I needed a duplicate of associative array so I wrote myDict.dup, which 
failed to compile (I use DMD 2.046). So I looked into the official 
language spec, which doesn't mention "dup" property for associative arrays.
The only trace I found on the Internet is in the preview of 4th chapter 
of TDPL (I'm still waiting for my copy from amazon.co.uk, which I hope 
will be dispatched before August), which, at the top of page 124, 
claims: "To create a duplicate of an associative array, use .dup, which 
works the same as for 10 arrays."
So... is it a bug or is this feature missing intentionally?
What would you recommend for concise, fast and safe surrogate?

AM