It is a coincidence that the first film outside of the Pat & Mat series that was discussed at greater length was Narkoblues, but it's not much of a coincidence that it was a film directed by Břetislav Pojar. Pojar was one of the best and most famous Czech stop-motion directors of all time and many would say he was second only to Jiří Trnka, his mentor. Pojar, however, lived much longer (1923-2012) and so was part of almost the whole history of the art form in Czechia, which is why he cannot be skipped in any story about Czech animation. He even had direct involvement in one Pat & Mat episode, writing 2003's Natírají podlahu.
Pojar's most famous directorial work, both home and abroad, is the Pojďte pane, budeme si hrát (Hey Mister, Let's Play!) series of shorts about two teddy bears. If you haven't seen these films before, well, what are you waiting for?!
If you aren't familiar with this series, here is a brief comparison with Pat & Mat. Both feature two main characters, but here our heroes are younger and also different from each other, much of the humor coming from their interaction, penned by Ivan Urban. They encounter other animals throughout in their forest-like worlds. An important difference is that the two bears speak, which, I presume, is one of the reasons why this series didn't receive that much international success. However, that won't be a distraction to you (see why down below).