Missing data on import

I backed up a website using AIO Migration and imported it. On the imported website I saw that 2 code snippets I had in the WP Code plugin on the main website were missing on the imported ones. Now I have trust issues with this thinking that if these were missing, who knows what else is missing? Why would the plugin miss those (or other data?). How can I be assured now that this works correctly and I can safely use it to migrate without data loss? Check your code.