Personally I use if self moving to resource keep moving to same resource,
If self not moving to resource move to resource ally isn't moving to.
If the only existing resources are being moved to by allies, then just default to move to closest resource.
The result is often bots will move to the same closest resource if they decide to move to a resource at the exact same time (which occurs if for example an enemy just died or moved out of range for both bots at the same time). But if each bot staggers the decision to move to resources then they'll each go to new resources.