If you check in a new package to ePO into a branch that contains a previous version of the product, any associated client tasks are blanked out; this prevents the task from upgrading the client by checking in new software. But, to update the task on the client, the client must communicate with ePO. If the client hasn't yet communicated with ePO, it downloads the product version that exists in the repository, and if it's a higher version, that new version is installed.

This can also occur if the task is scheduled to run immediately. Since there's a change to the task, the client runs it again.