'to have someone do / doing something' is quite informal, but the difference is comparable to the difference between simple and continuous.
- 'If you don't want to teach the children, just have them make a poster for an hour' (speaking generally, or a suggestion)
- 'He doesn't want to teach the childen today, so he has them making posters' (right now)
- 'When I went round, he had his kids working in the shop' (at the time that I was there).
It's a very informal structure though and I wouldn't say it's so common.
I hope that helps,
I hope that helps.