I don't understand those Dendroscope network distances

[lutteropp]

Why do trees with (unrooted) RF-distance of zero have non-zero Dendroscope distances? Does it have to do with the rooting somehow?

See screenshot from a results.csv file, used (in different settings) on a 4 taxon simulated tree:

I also attached the entire CSV file small_tree_results.csv.txt

In general, I still need to figure out how to interpret those topological distances computed by Dendroscope. Like... which number is good? What's the theoretical maximum distance? Can we convert them into relative values somehow?