All of the contracts were based on AMOS-6 being operational by a given date, AMOS-6 has been "under construction" for probably 4-5 years, SpaceX was selected as the launch contractor in late 2012 originally for a mid 2015 launch but the launch was delayed for various reasons.
They very seldom do, at least for non-constellation projects. Cheaper just to pay the insurance premiums for loss of hardware and loss of earnings.
Unless you're a Raman. Then you'll build three.
Although whether it would cost an additional $200 million to build a second is another question, but I doubt there would be that significant an economy of scale for just one extra unit.
Think of it like this if you total your McLaren P1-GTR there isn't an easy way to get a new one ;)
Why not?
[1] Which also seems to be a problem at Tesla as of late.