<form id="gonderform" enctype="multipart/form-data"> 
<input type="text" name="gidenveri1">      
<input type="text" name="gidenveri2">    
<input id="buton" onclick="ajaxGonder(1);"  name="birinciform" type="button" value="GÖNDER"/>    
</form>
<form id="gonderform_2" enctype="multipart/form-data"> 
<input type="text" name="gidenveri1">      
<input type="text" name="gidenveri2">    
<input id="buton_2" onclick="ajaxGonder(2);" name="ikinciform" type="button" value="GÖNDER"/>   
</form> 

<script>
function ajaxGonder(v){
if(v==1){
var veri = $('#gonderform ').serialize();
} else {
var veri = $('#gonderform_2 ').serialize();
}

... ilgili ajax kodları
}
</script>