testa ae, qualquer coisa posta ae! function envia(pId){
if (pId == "btn1")
document.form1.action = "01.htm";
else
document.form1.action = "02.htm";
document.form1.submit();
}
<form name="form1" method="post" action="">
....
<input type="button" id="btn1" onclick="java script: envia(this.id);" />
<input type="button" id="btn2" onclick="java script: envia(this.id);" />
</form>