shortestpathtree does not return multiple paths

I am trying to determine shortest paths from a source node to every other node. All weights are 1. When I use shortestpathtree, matlab does not return multiple shortest paths. For example, going from node 1 to node 9, shortest path is 1-10-9, 1-12-9, 1-11-9 but shortestpathtree only returns 1-10-9. Please advise. Thank you!