Can a node have two parents?

I had an idea regarding this: How feasible would it be for me to add a new flag to NodePaths/Nodes (the latter, I imagine, but accessible through the former) that indicates whether a Node may be multiply-rendered, with a guard added during scene-graph traversal that skips a node if it has been rendered before?

Something like this, in pseudocode:

Node:

bool mayRenderMoreThanOnce;
bool hasBeenRenderedThisPass;

In the scene-graph code:

// While traversing the graph...
if (currentNode.mayRenderMoreThanOnce || !currentNode.hasBeenRenderedThisPass)
 {
  currentNode.hasBeenRenderedThisPass = true;
  // Render the node as usual...
 }

Of course, this would presumably call for some means of clearing the “hasBeenRenderedThisPass” flag… Perhaps

I’m not currently using instancing, so there’s no conflict there. (In any case, the “mayRenderMoreThanOnce” flag could simply be set for instanced nodes.)

Thoughts?