Are there magnets with only one magnetic pole?
We don't carry monopoles, meaning magnets with only a north or a south pole. To our knowledge, it is not possible to produce a permanent magnet with only a single pole. Every magnet has at least 2 poles, a north and a south pole (see FAQ about north pole).
The existence of magnetic monopoles itself does not contradict current popular theories. They were even postulated by famous physicists (e.g. Paul Dirac) and there are serious current experiments that are looking for such formations.
They say that there may have been microscopic structures detected in all-solids, which look on the outside like magnetic monopoles. However, they seem to be bound to the structures in the all-solid. They can't be accumulated to a magnetic cluster that constitutes a monopole. If that was possible, the people who research this would have done that already and received a Nobel Prize for it.