Prueba esto:
Código PHP:
<html>
<head>
<script language="JavaScript">
var pop1, pop2, pop3;
function abrir(nPop){
if (nPop == 1) pop1 = open("popUp1.htm", "_blank");
if (nPop == 2) pop2 = open("popUp2.htm", "_blank");
if (nPop == 3) pop3 = open("popUp3.htm", "_blank");
}
function cerrar(){
if (pop1) pop1.close();
if (pop2) pop2.close();
if (pop3) pop3.close();
}
</script>
</head>
<body>
<form name="formulario">
<input type="button" name="crear" value="Abrir Uno" onclick="abrir(1)">
<input type="button" name="crear" value="Abrir dos" onclick="abrir(2)">
<input type="button" name="crear" value="Abrir tres" onclick="abrir(3)">
<input type="button" name="destruir" value="Cerrar" onclick="cerrar()">
</form>
</body>
</html>
Saludos.