To provide an option in a poll, you need to enter some text then click "Add Option". If two text boxes were available, users would forget to hit the "Add Option" button and would end up without poll options.
This is the default setting in phpBB anyway for good reason IMO. It means that the polls are more likely to be right first time instead of having to be edited to fix it.
i agree with animal ... hmm what a strage nick ...anyway lol .. it does tend to reduce the amount of mistake one would normally make when creating a poll .. thought it was rather weird the first time myself but got used to it eventually