registros repetidos..

[zaetoner]

entonces cambia esto:


if ($w = mysql_fetch_array($res)){
echo ' <select name= "mascota" style = "width: 190px"> ' ;
echo $sql;
do {
echo '<option value= "'.$w["IdMascota"].'">'.$w["IdMascota"].' --> '.$w["NombreMascota"].' </option>';

} while ($w = mysql_fetch_array($res));
echo '</select>';
}

por esto:

echo ' <select name= "mascota" style = "width: 190px"> ' ;


while($w = mysql_fetch_array($res)){

echo '<option value= "'.$w["IdMascota"].'">'.$w["IdMascota"].' --> '.$w["NombreMascota"].' </option>';

}

echo '</select>';