At the time of writing, areas around the Northern Territory (TC Lam) and Queensland (TC Marcia) in Australia are in the path of severe cyclones (category 4 at the moment, with the Queensland one - TC Marcia predicted to reach category 5 - Category scales used for Australia and Fiji). These cyclones seem to be connected by a monsoonal trough, as indicated by the dashed line in the weather map below from Australia's Bureau of Meteorology:
Note: it is summer here at the moment.
Also, these cyclones are a very large distance apart (about 1900km in a direct line), and these cyclones are not merging at all. According to the Meteorological Bureau, TC Lam is moving south through the Arnhem Land area of the Northern Territory; and TC Marcia is going to 'hook' when it goes inland and head towards the Brisbane area to the south coast of Queensland (but it is expected to weaken to a tropical low well before then). The projected paths (based on latest and consistent information from the Bureau) is shown as red arrows in the image below:
What is the meteorological mechanism that has resulted in the linked "double" severe cyclone event?
Edit - update: TC Lam has made landfall at cat 4, TC Marcia is now making landfall at cat 5