The greatest instance of vote-splitting I have ever seen resulted in the naming of Thunder Bay.

In 1969, the City of the Lakehead Act [...] decreed that Fort William and Port Arthur would amalgamate as of January 1, 1970, creating a new, larger city. Citizens were asked to select the city's new name by vote, with three candidates to choose from.

The final tally:

Candidate name Votes
Thunder Bay 15,870
Lakehead 15,302
The Lakehead 8,377

References