When deleting a task, the next launch associated with this task is deleted also.
Updating the scheduled launch without modifying anything, just by selecting update and confirming by validating with Run button, the behavior changes. So if Task is deleted then the associated launch does not disappear anymore and if the Task is imported again there are two launches at the same time.
This behavior is explained in the documentation.
Update of a Task and its Corresponding Launch
Cause: As soon as you update a Launch created by the Calculator (of a Task), the affiliation with the task disappears and for this reason deleting the Task does not affect this Launch.
USE CASE: A Task exists and schedules a Launch. Application requests to change variables values, schedule time and the submission user. It's an exception, but needed for the production day. Updates are done on the Launch. An update of the task is also requested to add a date of run, the task is updated. In this case, we will keep the current launch, because have specific update for the day. Globally, an update of a task request the check of launches to confirm that the modification is taken into account or if there is something to do manually.
Release : 6.x
Component : DOLLAR UNIVERSE
Product Enhancement Request raised in PMDU-2668 to change this behavior in the future.