hahah, that's a darn good question Jessie. Im not sure if it's the case with this specific scenario, but in short - YES, (especially w/ Outlook's variety of rendering) it's possible for something in the code to make a difference for one Outlook and not the other. It also looks like the one that's messing up is the 120dpi version which is for "zoomed" in displays so what you're seeing there is a scaled-up version of your email. Notice the width of the image is consistent with the rest of the display, but the width of the body is "zoomed in" (wider) than the rest? That's what's making me think the image is staying in the 600px frame and not "zooming in" with the rest of the email.
Im not an expert on VML code and frankly, I do my best to avoid things like that b/c they're error prone and very particular to size. I'd guess this has something to do with that tho since the rest of the Outlook's (which dont use the DPI scaling) are showing up ok.
This article: https://litmus.com/community/discussions/151-mystery-solved-dpi-scaling-in-outlook-2007-2013 explains a bit more about it and proposes a soultion using inline styles to declare the dimension instead of the height="" and width="" attributes. I usually will write those to be redundant, including both the attribute value for each as well as the inline style: style="height:__px; width:___px;". Maybe that'd help here?