Alternator/Starter motor issues

[DStanley1809]

A couple of months ago I replaced the alternator on my dads Range Rover. Since then there have been no problems with the battery or charging.

Today I had to replace the starter motor. As soon as we started up after putting the new motor on the dash computer flashed up alternator fault. The new motor fires the engine instantly.

A multimeter across the battery shows 12v when the car is turned off and 11.7v when the engine is on and the alternator is supposed to be topping the battery up.

Can an incorrectly wired starter motor A) start the car as normal and B) cause the alternator to break?

Or is it more likely to be a coincidence? It just seems strange that the alternator fault appeared the second we fired the car up with the new motor.