VPI Support

I purchased new belts from VPI. They supplied 2 belts for motor to flywheel and 1 belt for flywheel to platter. I purchased the TT and motor used and it came with only 1 belt for each application. I figured that both motor belts were to be used at the same time, as this is how VPI sent them. When I mounted the belts this way there is a significant vibration on the smaller motor belts upon start up. This goes away in about 2 seconds, and everything smooths out to normal. When only using 1 motor to flywheel belt there is a bit of vibration for maybe 1/2 second. My question is why is this happening? Is it normal? What is the proper way to set up the belts; 2 or 1 belt? Am I overthinking this?

Thanks, John