Trying to avoid the situation, where you have multiple time entries (to one, same task) it’s good to have in mind that there is a setting allowing you to modify time in an already existing entry.
Let’s refer to a situation in which you create a time entry and for some reason, you stop the timer. After a while, you decide to continue it – not necessarily wanting to have it placed as separate time entry on your Timesheet. In that case, you just need to go to Timesheet settings(1), disable “Autocomplete fields duration and from-to”(2) and unable “modify time in existing entry”(3) – as it has been shown on the picture below. This way you will be able to track on previous time entry, without creating a several numbers of them.