So you are asking if you uploaded 2 photos, (a) 900px by 100px and another 100px by 900px for them to display in same size and same proportion? They can, as a 100x100px image.
You have two options in Wordpress if you don't want to resize all the images manual - You can tell wordpress to crop the image based on predefined parameters, or you can tell wordpress not to crop the image but to proportionally scale it down until a predefined parameter is met. so if you redefine width and height for a particular part of the theme (in functions.php look at lines 20-30 or so.
Or you can use this plugin http://wordpress.org/extend/plugins/simple-image-sizes/ and in Settings > Media you will get the ability to see all the images sizes for the theme as well as WooCommerce and set the size and whether to crop or not.. You will need to regenerate all images once you change image settings in order for the already uploaded images to reflect the changes you made. The regenerate button is part of the plugin as well.