Continuo a pensare che stai complicandoti la vita senza sfruttare le potenzialita' di HTML e ASP.

Semplifico:
codice:
<form target="main" name="maxi" action="altra_pagina_stampa.asp"> 
<input type="checkbox" name="id_c" value="id_c"> 
<input type="checkbox" name="id_N" value="id_N"> 
<input type="checkbox" name="id_F" value="id_F"> 
<input type="checkbox" name="id_S" value="id_S"> 
<input type="checkbox" name="id_A" value="id_A"> 
<input type="checkbox" checked name="id_T" value="id_T"> 

<input type="button" value="Tabulato 1" title="Stampa" 
onClick="this.form.action='ga_6_stampa_1.asp?ts=1'; this.form.target='miaPop'; window.open('','miaPop');">

<input type="submit" value="Tabulato 2" title="Stampa" > 
</form>
ciao