The solution is to separate the layout of these pages from their content.
I assume that you want the same general appearance for the corresponding pages in all languages. So instead of copying the pages for each language and changing their content:
- create a template page that has some placeholders or variables
- write the content for each language variant so that it provides these variables
- render the actual pages by filling in the placeholders in the template with the content for the correct language.
Many Content Management Systems have plugins that can help with translations and internationalization. If have developed your website from scratch, it's also easy to implement a basic translation system yourself.
The difficulty is that you often don't want to translate every page in every language. So sometimes you will still have to fall back to copying a page and editing it for one language only. But in principle you can freely combine these approaches.