Yes, there is. You can create clones of Object3Ds by using the constructor that takes another Object3D as input. If they should share geometry data in the vm memory, use that one with the boolean reuseMesh-flag and set it to true.
If it's jPCT-AE or jPCT with compiled objects, you can make such objects share the same data on the GPU too by calling shareCompiledData(...). If textures and coordinates are also the same, you can use shareTextureData(..) in addition.