Why does MRA say a name already exists after I deleted the entry?
Where to find it: Financial-entry form; SAVED RUNS & SCANS
Deleting an expense, income or another saved-scenario item can remove it from your current scenario while retaining it internally because a saved scenario still refers to it. That lets Restore bring the original entry back.
The name check can include these retained entries. This is why an expense name can still be unavailable even though you no longer see that expense in the current list.
Use a different name for a new entry. The retained original can be permanently removed once the saved scenarios that require it have been deleted; deleting those saved results also removes your ability to restore them.