Does exist any speciality where is it possible to see more that one team from the same Country at the World Championship events?
It very definitely happens in a number of sports. I can immediately think of bob-sleigh, where it is very common in both Olympic and World Championship competition to have multiple teams from the same country. In the most recent 4 man bob world championships Germany finished 1,2 and 4 
The answer here is going to depend a lot on how you define "World Championship" and "team" (in particular, is one person a team?), so here's a community wiki list:
- Beach volleyball: this definitely has a World Championship, and multiple pairs from one country can enter.
In the 2000 Rugby League World Cup both New Zealand and a New Zealand Maori team competed alongside each other. In terms of the major "team" sports (eg Soccer, Rugby, Cricket etc) this is the only occasion that this has happened.