Currently we cannot create a new task in a project with the name of an existing one.

But usually, when we are re-discussing a project with client, arrive a moment when we are reviewing a task rate.
So we have :
"Task 1" - Rate 100$ in 2016.
Then after rediscussion we will -
- deactivate "Task 1"
- create a new "Task 1 - Rate 2017" - Rate 110$

But basically for the client, this is the same task / item. Only the price has changed.
As that name (might) appear on the invoice, this is not very client friendly.

It would be better to be able to create a task with the same name as another one (only for deactivated tasks), but being able too add an internal comment to explain the task (eg here "2017 - contract renegociation")