It would probably look suspicious, but it is theoretically possible.

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Last year, I had two exams on the same day (one at 9 am and the other at 4 pm). I normally don't manage to fall asleep the nights before my exams (I usually have trouble sleeping anyway, but having an exam makes it much worse). I didn't sleep at all the night before, went to my first exam and did fine, went to my second exam and had a panic attack in the first 10 minutes. I put my hand up and told the invigilator I can't continue writing (I actually hadn't even touched my paper). They took me to another room and asked me some questions and then had me leave and I wrote a deferred exam. Apparently my face was so pale they asked if I wanted them to call medical assistance...

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So it is possible to defer one of two exams on the same day, but in my case I don't think that was your typical deferral.