MER 1 & 2 were govt. built, with subcontracts going to LockMart
To answer your question:
*MER 1 & 2 were government (well, JPL) built, with subcontracts going to LockMart for stuff like the aeroshells.
As for the supposed lack of competent competitors for Lockheed regarding Mars, one could make a similar defense of some company's potentially requiring that all employees use Microsoft's Internet Explorer instead of NetScape. Presumably you're familiar with how Microsoft unlawfully squashed that competitor though...
Imagine how many more competitors for Lockheed could flourish with the implementation of just a few pro-entrepreneurial reforms that wouldn't cost taxpayers more:
http://www.spaceprojects.com/reforms