exact
The ring was an exact duplicate of her mother's ring.

create, make
We made a duplicate of the key.

in duplicate
The contract is prepared in duplicate, so that both parties can sign it.

exactly
The original experiment cannot be exactly duplicated.

simply
I wanted to avoid simply duplicating work that had already been done.

easily (esp. AmE)
This is a natural look which you can easily duplicate at home.

Duplicate is used with these nouns as the object:
CD, CD-ROM, disk, effort, feat

Duplicate is used with these nouns:
copy, key