Unique ID with shared content field

[Thyago <ts...@gmail.com>]

Hi,
Is there any way to commit docs with unique key but with shared content ?
Example:

<field name="id" type="string" indexed="true" stored="true" 
required="true" />
<field name="code" type="int"    indexed="true"    stored="true"  />
<field name="content" type="text" indexed="true" stored="true"  />

I have a lot of itens with same content but with different codes.
Because this index is very large there any way to commit docs with 
unique id and
code but with shared content to have a smallest index ?

[]'s
Thyago