Do VSD offer the equivalent of torque control for this sort of thing?This can be a simple 2 contactors with overloads pulling in with the same coil signal or we can get very complex and fit vsd's that track as a master and slave... depends on the nature and precision required.
For big DC servos that needed zero backlash it was a common trick to have the armature current deliberately offset by a small-ish amount so the two motors would have a more or less constant tension between them to take up free play on the drive train, but I have never had to look at the AC motor equivalent (so far).