If your contract is "all your work are belong to us", then it can have some funny legal consequences with each company claiming ownership of the entirety of you

If your contract is "all your work are belong to us", then it can have some funny legal consequences with each company claiming ownership of the entirety of your work. More important are trade secret issues. These are treated very seriously and can result in criminal penalties. So be super careful here - though different industries certainly help. Not sure about the carrier consequences. Don't put overlapping jobs in your resume and make sure all your employers are satisfied. Quit some of your jobs if you're overwhelmed.