Insert statement runs twice - php

Question

I am trying to build some sort of database class (all PDO). All my functions work up till now, but the insert statement runs twice. I really don't see where it goes wrong. When I run the code with some echoes in it, the echoes only appear once so I don't think that it actually gets executed twice...
When I use the getBind function with other statements it works perfectly fine so...
THE CODE
function insert ($p_sTable, $p_aCol, $p_aVal) {
$this->m_sQuery .= "INSERT INTO ".$p_sTable." (";
$queryCols = "";
foreach ($p_aCol as $col) { ... }
$this->m_sQuery .= $queryCols.") VALUES (";
$queryPlaceholders = "";
foreach ($p_aCol as $placeholder) {... }
foreach ($p_aVal as $p_aValtosave) { .... }
$this->m_sQuery .= $queryPlaceholders.")";
echo "m_sQuery:</br>".$this->m_sQuery;
echo "</br>print bindCol</br>";
print_r($this->m_aBindCol);
echo "</br>print bindVal</br>";
print_r($this->m_aBindVal);
return $this;
}
WHERE I CALL THE FUNCTION:
$db = Db::getConnection();
$arr = $db->insert("geprutsvanlisa",["kolom1","kolom2"], ["24", "24"])->getBind();
THE OUTPUT: m_sQuery:
INSERT INTO geprutsvanlisa (kolom1, kolom2) VALUES (:ikolom1, :ikolom2)
print bindCol
Array ( [0] => ikolom1 [1] => ikolom2 )
print bindVal
Array ( [0] => 24 [1] => 24 )
echo i:0
bindvalue(:ikolom1, 24)
echo i:1
bindvalue(:ikolom2, 24)
echo this ms query
INSERT INTO geprutsvanlisa (kolom1, kolom2) VALUES (:ikolom1, :ikolom2)
echo this bindcol Array ( [0] => ikolom1 [1] => ikolom2 )
echo this bindval Array ( [0] => 24 [1] => 24 )