We have a requirement that we don't want to translate/update translated content on a component in language copies. We have in the past send the english page(containing the component) for translations and now want to keep separate content in language copies. But when ever we send the english page for translations it updates the language copy. I have removed the property from translation_rules.xml file still facing the same issue.
I believe you need to define translation rules. Refer to  for more details.
Translation rules identify the content to translate for pages, components, and assets that are included in, or excluded from, translation projects. When a page or asset is being translated, AEM extracts this content so that it can be sent to the translation service.
Pages and assets are represented as nodes in the JCR repository. The content that is extracted is one or more property values of the nodes. The translation rules identify the properties that contain the content to extract.
Translation rules are expressed in XML format and stored in these possible locations: