I have a busy job so I only mystery shop a little. I mostly do food shops - fast foods for lunches and restaurants for dinner or weekend meals with friends. I do retail or service only if it looks fast and easy and I need whatever it provides. I started mystery shopping in 2011 after my brother started about a year earlier. He was signed up with Market Force so I signed up with them, too. We have both continuously shopped for Market Force, and other companies, ever since. We share a residence and have the same ip address, each with our own phone number. Some companies have asked that we upload drivers licenses, but no company has declined to allow us to both work. As for Market Force, my experience has been like Mert. Two shoppers who are related and/or live in the same household seems not to be a problem to Market Force as long as things go smoothly. However, if one person in the household (or a person closely related who lives somewhere else) gets deactivated, Market Force deactivates all roommates and/or family members. It's my belief that they do this because, having deactivated a shopper, they want to be sure that shopper has no access to Market Force and they deactivate those close to the shopper to make sure. So once they cut you off, they cut off anybody who is related to you. I could be wrong but that's my impression from seeing friends' experiences. So far neither my brother or me have been deactivated.