With older versions, I could overlay isodose lines of two RTDOSE files using the isodose tool. But, with the latest version 5.3.0-2022-11-26, I cannot do it anymore. It replaces the isodose line plot when I generate isodose lines after changing the RTDOSE file.
Yes you are right, this is a regression. Can you please add an issue to Issues · SlicerRt/SlicerRT · GitHub about this? I will try to fix it soon, when I get to work on this module. Thank you for your report!