Contracts have to be upheld by a court, to mean anything. I could write in a contract that you will be required to hand me your testicles if you miss the deadline, that doesn't mean I will actually go to court to get them. A lot of companies write aggressive contracts and never actually bother to enforce them, since it would be more costly than what they might actually gain.

Legally, yes - But remember that those provisions are there because someone tried that in the past and so they added legal provisions against it. And remember that those legal provisions are hard to prove; What is 50% of the work? How would they know if he'd had another developer submitting code?