What is the max span on doubled up 9.5 in microlam that's carrying 16 in oc 2x10 for a loft?

Several factors affect the allowable spans. Each manufacturer of laminated beams have specific load limits and allowable spans. The total load that is going to be placed on the beam should also be factored into the equation. Heavier loads will require more support, reducing the maximum span allowed. If the manufacturer cannot be determined, then local building codes should be consulted. Building inspectors can be contacted to help you determine the appropriate span.