[TASK] 42563 Added check for duplicate passwords and getRecords operation

This task was taken from tomasnorre - I patched issue #42563 from Forge (http://forge.typo3.org/issues/42563) and submitted this possible solution to the problem.

It suggests a GetRecords operation with a similar API but different behaviour. Take a look at the inline comments

I would like a review and comments/suggestions (as if I can avoid them ;) ).