Merging results of facet fields

[Marc SCHNEIDER]

Hello,

I have two fields 'product' and 'tag'.
Executing this query q=*:*&facet=true&facet.field=product&facet.field=tag
gives me this result :

<lst name="facet_fields">
  <lst name="product">
     <int name="computer">16</int>
     ...
  </lst>
  <lst name="tag">
     <int name="computer">7</int>
     ...
  </lst>
</lst>

Is there a way to group the results by value ie getting <int
name="computer">23</int>, regardless of the field names?

Thanks in advance,
Marc.