Escapes get lost when saved in the RichText-Editor

Certain escapes get lost after saving a page in the RichText-Editor (it doesn't happen in the Wikitext-Editor). For example:

we enter in the Wikitext-Editor: @asdf@ in order to get "@asdf@" in the page (literally, not as template text field)
if we now edit the page again and switch to RichText-Editing, the RichText-Editor converts it to @asdf@ which, when saved, is being rendered as a template text field. The escape gets lost.