When zooming in with your browser, it is not uncommon for elements to crash into each other. It's best not to dwell on this issue too much. However, ensure that your images share a common parent element with the CSS property "position: relative".
Here is an example of how you can structure your HTML and CSS:
<div class="myImageContainer">
<img class="positionedRelative" src="" alt="" />
<img class="positionedAbsolute" src="" alt="" />
</div>
CSS
.myImageContainer { position: relative; }
img.positionedRelative { position: relative; } /* You may consider removing this line if unnecessary */
img.positionedAbsolute { position: absolute; left: 0; top: 0; }
Feel free to customize the values of "left" and "top" according to your needs.