Size parameter + duplicates

Hi all,

I am using boolean queries to retrieve index entries, setting the size
param to a preset resultset size.
When the matching documents are less than the preset max, I get duplicate
results to match the "size" requirement.

This is how I build the query:
String json =
"{"fields":["url","tv"],"size":"+Urls.size()+","query":{"+
""bool":{"+
""must":["+
"{"term":{"eid":"+eId.toString()+"}},"+
"{"term":{"cid":"+cId.toString()+"}},"+
"{"terms":{"url":["url1","url2",...,"urlN"]}}]}}}"

Is there a way to retrieve unique results?

thx in advance,
Dionysis