Connector Current Carrying Capacity (circuits in paralllel)
Assuming you are not planning on hot connecting the connector, it is safe to simply multiply by the number of shared connections. 

However, it is best of the shared pins are next to each other. Having them on different sides of say a ribbon cable creates loops that can cause noise issues.

Also, the quality of the connector makes a difference. Cheaper connectors may only make on one of the two pins leading to a higher current on the other. This should not be a problem in your case since the total current is under the maximum for a single pin.