Until the 60’s, a single synchronous motor drove an M-G set (Motor-Generator set). This contained several generators on one shaft driving one or more motors each. DC motors and generators were used at that time.
When static drives became available, they were often used with more than one motor. The reason was to save cost. Often the drive would power a main roll and several nearby rolls. In the paper industry these are called Paper Rolls (Driven “Idler Rolls”) or tension rolls.
As the price of drives fell, we implemented a one motor one drive policy. This is common in web handling industries today.
There are a few instances where powering several motors with one drive makes a lot of sense. That is for driving multiple rotating slitter anvils and for conveyors where several motors are required. It is nice to know that all the slitters are running at the same speed.
AC drives can be tuned for several motors. A few guidelines should be followed. It is easier to control the load if the motors are nearly the same or identical power. They should drive nearly the same inertia. These guidelines help in sharing load, especially during speed changes or during an Estop. A large motor is capable of generating into a smaller motor during an Estop and tripping the smaller motor on overcurrent. The current transformers in the drive do not even see these circulating currents. A single drive can do nothing to prevent circulating currents between motors.
It is a good idea to have separate contactors and overload protection for each motor. The electrical code in your jurisdiction must be followed.