demo.py

from weasyprint import HTML

document = HTML(filename="./index.html").render()
duplicated_pages = document.copy(document.pages * 2)
duplicated_pages.write_pdf("result.pdf")

index.html

<style>
html, body {
    background-color: #ffeecc;
    color: #0013ff;
    font-family: "Neue Machina";
    padding: 0;
    margin: 0;
}

@page {
    size: 64mm 37mm;
    margin: 0;
}

#paper {
    position: relative;
    width: 64mm;
    height: 37mm;
    background-color: white;
    border-radius: 2mm;
}
</style>


<div id="paper">
    This should be printed twice, but is not.
</div>