While trying to add timeline with same time for different dates it shows error.

[Sujatagp]

Steps to reproduce

1. Login to timetracker.
2. Open any task which has old date timeline.
3. Add same start time as previous date timeline and save.

Expectation
Should allow to add timeline for new dates.

Observation
It shows error.

[Sujatagp]

On try of adding new timeline, it is showing task name exists.