Starter keeps running

The hanging bendix can get spooky sometimes. I replaced the starter on the minivan of an elderly friend because it had an intermittent no crank problem. The first replacement starter did not disengage from the flywheel, so off the the auto parts store for another one. It did the same thing - drag and spin after the engine started. Off to the auto parts store a 3rd time to get a refund and then go to a different auto parts store to get another brand remanufactured starter. The 3rd starter fixed the problem. The first two were evidently from the same production batch and had been assembled incorrectly.