There's nothing inherently wrong with your idea. Most can adjust to running for time, rather than for distance, pretty readily; and doubles have been demonstrated to increase fitness more than singles. However:
Depending on your speed, your weekday running (AM hour + PM hour) would total maybe 15-20 miles a day. Add on your weekend runs, and that's a significant increase over your current mileage, at a time when there are other changes in your life (and all change, even good change, is stressful and drains some of your reserves). Ordinarily we wouldn't look for an increase in running volume or intensity when adapting to major life changes--a month or even two of "maintenance" running is called for, until you get adjusted. So, yes, be alert for burnout.
Here's a tip that I got from somebody's (Ron Clarke's?) book. Set the alarm for when you *have* to get up in the morning. If you get up before that without the alarm--fine, go get your morning run. If you wake up *with* the alarm (= no time for morning run), then you needed the rest anyway.
Also, get in the habit of taking your pulse for a full minute upon waking (before getting out of bed). If your pulse is up on a given day, particularly if it's up 10%+ above your normal, then you haven't recovered completely and you need to back off on (or skip) the running for that day.