Mecanum Wheels Drive Chain Problem

[Alectrolytes]

When we test our mecanum wheels, going forward and backward is fine. However, when we strafe left, our robot tends to go forward as well, when we strafe right, it goes backwards. After jacking up our robot, we notice 2 wheels (wheels 1/FL and 4/BR) spin faster than the other wheels. I can't diagnose the problem since we thought it was a calibration problem. Maybe we're doing it wrong, any tips for calibration? Perhaps we're mixing up different CIM motors with different specs?