I believe it’s possible to use two CDMA sims if they are both on the same plan. In your case it would be a corporate plan and a personal plan. I may be wrong altogher as the information on this scenario is pretty vague.
Also some corporate phones are provisioned in a such a way that you will not be able to use a personal line at all. You need to verify this with your employer.
Yes assuming your employer hasn’t limited your option, you should be able to use Verizon with Tーmo