Integrate 2 maps side by side

Hello guys,

On my site, the university I'm working for has 2 addresses. So I want to integrate both maps side by side. https://geographie-cites.cnrs.fr/acces/ When I have the same Iframe code, it works, see the first block on my page. But as soon as I have 2 different code, only 1 column is displayed, the second one disappears, why? (it was working perfectly with Google maps iframe code) Tx for your help Marine