The following information is taken from the Dictionary of the Older Scottish Tongue, available online at http://www.dsl.ac.uk/index.html. This is a work in progress.
| Spelling | Number | Dates & headers |
|---|---|---|
| Duncan | 5 | 1529 (clos); 1558-9 (bounteth); 1561 (civily); 1616 (brew cresch); 1641 (brasche); 1642 (bowat) |
| Duncane | 4 | 1590 (clim, croce); 1607 (copper); 1648 (condescender) |