DNA Topology of two circular chromosomes
Yes, there is an abundance of evidence. I think the following electron micrograph is pretty convincing.



This image is from a review:

Gil-Ramirez G, Leigh DA, Stephens AJ. 2015. Catenanes: Fifty Years of Molecular Links. Angew Chem Int Ed 54:6110-6150.

It was adapted from the first paper to observe naturally occurring catenated DNA molecules, which were isolated from HeLa mitochondria:

Hudson B, Vinograd J. 1967. Catenated Circular DNA Molecules in HeLa Cell Mitochondria. Nature 216:647-652.

You can see this answer for an explanation of why catenanes form during replication:

How do catenanes form when DNA replicates?