Duke sits next to 4 phonetic neighbors — Luke, Huck, and Buck are the closest matches by sound. Most share Duke's English-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"leader, military commander"
"male duck"
"God will add, God will increase"
"spear, lance"
"God has helped"
"visitor, pilgrim"
"holy, sacred place"
"bald (short for Calvin from Latin Calvinus)"
"little red-haired one"
"little fawn"
"old friend, noble friend"
"from the city of lions"
"fair warrior, white hero"
"hollow, empty"
"son of Brice"
"rocky land, stony ground"
"dweller near the ridge"
"healer (from Greek Jason)"
"gift from God"
"brown, dark-complexioned"
"peddler, pack-horse driver"
Similar sound: These names share phonetic patterns with Duke — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Latin origins, giving them the same cultural heritage as Duke.
Rhythm: Duke is a 1-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.