The spelling of the word "Sydne" may seem unusual, but it is actually a phonetic representation of the popular name Sydney. The phonetic transcription of this name is /ˈsɪdni/, and the spelling "Sydne" represents a condensed version of this. The final "y" has been omitted and the "i" has been replaced with an "e". It's always important to remember that spelling variations like this can occur, but as long as the pronunciation remains the same, the message will still be understood.