If Insights Detailed Timesheet Excel shows two leave columns with the same name (for example Leave: Annual Leave (428) and Leave: Annual Leave (503)), Drum has two separate leave type records that share a display name. The export appends the leave type id when names collide so the columns stay distinct.
Why duplicates appear
Under Settings → Leave Types, Sync Leave Types imports leave types from Xero Payroll (Australian or New Zealand organisations with payroll access). Sync matches existing Drum leave types only by the Xero leave type id stored on the record. It does not match on name.
So if you create leave types manually (or import them during onboarding) and later run Sync Leave Types, Xero creates a second row for each synced type. Both can be named Annual Leave. Timesheet bookings and Xero leave import can then land on different rows, and Detailed Timesheet Excel shows both columns.
How the Excel columns are named
Leave columns are labelled Leave: plus the leave type name. When more than one leave type in the export shares that name, Drum adds the leave type id in brackets. The numbers are Drum ids, not Xero ids. The same rule applies to banked credit columns when credit type names collide.
Clean up duplicate leave types
Open Settings → Leave Types and confirm you have two (or more) rows with the same name.
Keep the Xero-linked row: the one created by Sync (or already linked for leave import). That is the row new Xero leave should land on. If you are unsure which is linked, stop and ask Drum support before deleting anything.
Move time off the orphan. Leave time booked against the duplicate must be re-entered (or reassigned) against the keep type. Archiving alone does not merge historical hours. For a large backlog, ask Drum support for help rather than editing week by week.
Archive the duplicate. On the orphan leave type, use delete so it moves to deleted leave types (View Deleted Leave Types). Optionally turn off Show on Timesheets first so staff stop picking it.
Do not run Sync Leave Types mid-cleanup. Sync can create more duplicates if names still lack a Xero id link. Finish the keep / move / archive steps first.
After cleanup, re-export Detailed Timesheet for a short test range. You should see a single Leave: Annual Leave column (no id suffix) when only one active leave type has that name in the period.
Avoid creating duplicates
If you will use Xero leave import, prefer Sync Leave Types (or have Drum link Xero leave type ids) before creating the same names by hand.
If leave types already exist without Xero links, ask Drum support to attach the Xero leave type ids instead of Syncing on top. Sync only skips a row when that Xero id is already stored.
Leave import behaviour is summarised in the Xero synchronisation reference.