Ahmet, you should be given a ranking boost by google merely for your due-diligence. But unfortunately they don't give a due-diligence boost.
One copy of text is not going to push you into the situation where google thinks you are keyword stuffing. They understand there are use cases like for example decorative text, where words may repeat.
One such use case is colored text, where multiple font glyph contain the different colors so the text is repeated (overlaying a diffent glyph of the same letters) for each color overlay. In this use case duplication is required.
1> One option is to use an image, which could be an svg giving a lot of decorative options.
2> Another is to use a canvas giving a lot of decorative options.
But these two options may not be as flexible to change content or in responsive layout.
color:red; // example style not 3d
<h2 >Sample Title</h2>
elements = document.getElementsByClassName("addeffect")
text = elements.innerText; // special use case -- see note below.
var span = document.createElement("SPAN");
span.innerText = text;
// note this is special use inline on each heading so removing the class will advance to next element.
// instead could be coded once on page instead but as a new class is dynamically added ...
// So usage could change to once per page. Hence getElementById not used intentionally.
<h2 >New Title Just added</h2>
<!-- run same script here for new title and it will not effect prior title -->