I ran twice the other day. Technically, it was not the same day, but it was 2 runs 12 hours apart. I had a late meeting at work. This means that I would be getting home about 2 hours later than I normally would. I would not be able to make it out for my run if I wanted to run after work.
I worked it out that I could arrive at work at a later time. This way I can go running in the morning before I go to work. This would also mean I would be running twice in the span of 12 hours. This is not the first time I would be doing this. Usually it is on Friday night / Saturday morning combo.
This is doable and will have no adverse on your running if you do it correctly. It also depends on your goals. My goal for these two days is to just get out there. I am more focused on the amount of days I run, rather than total miles or speed.
I usually go about a mile less on each run. Instead of 4 miles at night and 5 miles in the morning, I would run 3 miles at night and 4 miles in the morning. This keeps me from overdoing it and taking a chance of being injured.
Do you ever run twice in one day? If so, how do you do it?