Moving data from multi node to single node cluster

We have a 2 data node cluster (with a dedicated master) and we would like to move the older indices off to a backup cluster. The backup cluster is a single node server (master and data).

I have closed all of the older indices that we would like to move. We will eventually use curator for this, but in the meantime how do I move those indices? When it is a single node server, it is easy because I can just move the data to the elasticsearch/data/ directory. But how do I handle it when there are 2 data servers being merged into 1. Do I just copy the data from one of the servers (since it should be replicated)? Are there any gotchas with doing that?