Gallery post/different height of images/Masonry

Hi,
I added post with images gallery. The images is not the same height.
When the user is on the blog page and try to see images by clicking on the arrows there occur some problem with higher images. I mean the excerpt of the post is covered by the image of the below post. Is that means that I can upload as a gallery only the images with the same height?
Best,
M

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