Reconciling an IP agreement vs. IP provisions in Employment/Contracting contract

Thanks to everyone for all the previous and ongoing hard work on the documents here!

The README notes:

> Many employee IP agreements are very generous – to employers.

and...

> If you've worked in the technology space before, there's a good chance that you've run across one or more of these in the past.

Every employee or contractor is going to be signing an employment or contracting contract. These documents almost always contain IP provisions. These documents are referenced in the BEIPA:

> The Company owns any IP ("Company IP") that you create, or help create, during the term of your employment or contract work, within the scope of your employment or contract.

Is it the community's and by extension GitHub's experience that employment contracts they are using do not contain any IP provisions? Based on the statements above, are we collectively assuming they are at odds with each other? If not, does the community have experience integrating the terms in the BEIPA into employment contracts (one document seems highly preferrable to two)? If they are expected to be at odds with each other does the community have experience with dispute resolution to share?