iOS switch focus between selects – strange behaviour

This strange behaviour happened both on Chrome and Safari on iOS 13.3.
If I select one value from the first select options and switch to the second select the value (in the same position I think) is automatically selected.

Does anyone have faced this problem? Maybe I’m missing something obvious.

Video here

<!DOCTYPE html>
<html>
    <head>
        <title>Example</title>
        <meta charset="UTF-8">
        <meta name="viewport" content="width=device-width, initial-scale=1.0">
    </head>
    <body>
        <div class="form-group">        
            <div class="row">
                <div class="small-6 columns">
                    <label class="required">Number Adults</label>
                    <select id="NumberAdults" name="NumberAdults" style="min-width: 200px; font-size: 16px;">
                        <option value="ad1">ad 1</option>
                        <option value="ad2">2</option>
                        <option value="ad3">3</option>
                        <option value="ad4">4</option>
                        <option value="ad5">5</option>
                        <option value="ad6">6</option>
                        <option value="ad7">7</option>
                        <option value="ad8">8</option>
                        <option value="ad9">9</option>
                        <option value="ad10">10</option>
                    </select>
                </div>
                <div class="small-6 columns">
                    <label class="required">Number Childs</label>
                    <select id="NumberChilds" name="NumberChilds" style="min-width: 200px; font-size: 16px;">
                        <option value="nc1">nc 1</option>
                        <option value="nc2">2</option>
                        <option value="nc3">3</option>
                        <option value="nc4">4</option>
                        <option value="nc5">5</option>
                        <option value="nc6">6</option>
                        <option value="nc7">7</option>
                        <option value="nc8">8</option>
                        <option value="nc9">9</option>
                        <option value="nc10">10</option>
                    </select>
                </div>
            </div>
        </div>
    </body>
</html>

Source: Ios