Upload two featured images

Hello, good night. I'm currently working on the site visible at: www.elenafloreshuelves.com/pagedevelopment As of right now, when I post an entry and select a featured image, that images goes as a croped version to the thumbnail of the entry and as a main, large image at the header of each individual entry. I'm interested in knowing if there's a way to upload two different images, with two different sizes, to put each of them where it belongs. I believed I had found a similar question to mine, but as I kept reading it appeared like the original topic drifted away from my question, so I decided to open my own. If there is a way around this I'd thank you if you could please let me know or if its just advisable to upload the image with the right aspect-ratio for it to fit both places. Thanks in advance, Mariano G.