The reason for this is that Price 1 and Price 2 are compared with each other. If these aren't the same both are shown, with the latter in brackets.
This can be fixed by overriding product/price_listing starting from line 21
/* start remove */
$mainCurr = $this->currencyHelper->mainCurrency();
$app = JFactory::getApplication();
$currCurrency = $app->getUserState( HIKASHOP_COMPONENT.'.currency_id', $mainCurr );
$msrpCurrencied = $this->currencyHelper->convertUniquePrice($this->row->product_msrp,$mainCurr,$currCurrency);
echo "<br/>1: " . $msrpCurrencied . "<br/>2: " . $this->row->product_msrp . "<br/>";
if($msrpCurrencied == $this->row->product_msrp)
/* end remove but keep next line */
echo $this->currencyHelper->format($this->row->product_msrp,$mainCurr);
/* start remove */
else
echo $this->currencyHelper->format($msrpCurrencied,$currCurrency).' ('.$this->currencyHelper->format($this->row->product_msrp,$mainCurr).')';
/* end remove */