From Tučňák Wiki
If you write callsign which is saved before then Duplicate QSO dialogue is displayed. You have several choices, see below.
- Clear this QSO - clear this QSO (as F3 key), old QSO isn't changed
- Edit old QSO - edit changes in old QSO
- Mark old QSO as ERROR - Mark old QSO as ERROR, a new QSO is relevant now
- Store as DUPE - Old QSO is kept, new QSO has zero points and is logged as DUPE.