How can i only save non duplicate data from my php code to a txt file ? or only display non duplicate content from a content spinning?

i want to save data i created randomly in a txt file ,but only keep the non duplicate data and also only display on a broswer the non duplicate data how can i do it in PHP ?

i try to create different sentences with a content spinning code; but i encounter 2 problems the first one with my code i can't display non duplicate sentences , and when i want to save them into a txt file ,he ony take 1 sentence and do not write the others .

here is my code:

<?php

function RandomContent($txt)
{

    $pattern = '#\{([^{}]*)\}#msi';
    $test = preg_match_all($pattern, $txt, $out);

    $toFind = array();
    $toReplace = array();

    foreach ($out[0] as $id => $match) {
        $choices = explode("~", $out[1][$id]);
        $toFind[] = $match;
        $toReplace[] = trim($choices[rand(0, count($choices) - 1)]);
    }

    return str_replace($toFind, $toReplace, $txt);
}

    $role1= "{hero~king~president}";
    $role2="{warrior~soldier~pilote}";
    $text =  "\n" . "i'm not a ". $role1 . " but i'm a " . $role2;
   $numberOfSentences= 10;

    for ($i = 0; $i <= $numberOfSentences - 1; $i++) {

            echo "<pre>";
            echo RandomContent($text);

            $texttoregistry = RandomContent($text);

            file_put_contents('Random4.txt', $texttoregistry, FILE_APPEND);
            echo " || your data is registry into the ramdon file txt";



    }
    $lines = file('Random4.txt');
    $lines = array_unique($lines);

i had try several thing to try in a first time save all line i create with the ramdon function by using FILE_APPEND

and to delete them from the Random4.txt i use array_unique but this didn't work .

here is the result in my Random4.txt and also on a browser :

i'm not a hero but i'm a soldier
i'm not a hero but i'm a pilote
i'm not a hero but i'm a warrior
i'm not a hero but i'm a pilote
i'm not a king but i'm a warrior
i'm not a president but i'm a pilote
i'm not a king but i'm a soldier
i'm not a king but i'm a soldier
i'm not a king but i'm a pilote

what i expect is something like this :

i'm not a hero but i'm a soldier
i'm not a hero but i'm a warrior
i'm not a hero but i'm a pilote
i'm not a king but i'm a soldier
i'm not a king but i'm a warrior
i'm not a king but i'm a pilote
i'm not a president but i'm a soldier
i'm not a president but i'm a warrrior
i'm not a president but i'm a pilote

Can't someone Lead me to find a solution please ? thank you by advance