PCG Spline Alternating Meshes?

Hi, apologies if this is simple but I only just picked up PCG and I’m afraid I can’t find a solution. I’m looking for a way to generate a fence along a spline. The fence has alternating meshes meant to interlock together.
I’ve gotten everything the way I want it outside of the ability to alternate the meshes, unfortunately I simply can’t find out how to do it. Any pointers would be much appreciated. Its a simple alternation of Mesh A, Mesh B, Mesh A, Mesh B, etc.