[🐞] preloader script can contain duplicated keys

[maiieul]

This can increase the size of the html a little bit.

Repro: https://qwikified-threejs.vercel.app/ & https://github.com/maiieul/qwikified-threejs

[chebanenko]

Hi @maiieul,

Could you please check if my pull request resolves the issue?
Thank you.