Ask: We shouldn't allow agents to submit a time off request that overlaps with a previously approved request. Or we should at least warn the approver and force them to select between the conflicting requests

Why: Agents will sometimes forget that they already submitted a time off request and had it approved. Then, they will submit one that overlaps with that original request. When the second one is also approved, this creates conflicts on the Staffing Timeline that someone then has to manually resolve - this creates additional work when someone wants to save the Staffing Timeline view as a template.

It also results in the double counting of 'approved time off events' in Schedule Analytics.