The problem is that the method append()returns the selected item. In your case, this is an element .dynamic. After adding, you install html()from .dynamic, which then overwrites div, added to append().
To accomplish what you need, you can create an element divseparately before adding:
$('<div />', {
class: 'clipboardContent',
html: window[recentPerson].fullname + '<br><span style="color: lightgray; font-size: 10pt">' + window[recentPerson].mail + '</span>'
}).appendTo('.dynamic');
Working example
Or you can save your current method and include HTML in the line you add:
$('.dynamic').append('<div class="clipboardContent">' + window[recentPerson].fullname + '<br><span style="color:lightgray; font-size:10pt">' + window[recentPerson].mail + '</span></div>');
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