Tiles are double-shuffled at the beginning of every game, so each deal is completely random and it's nearly impossible you'd get the same tiles twice
What can sometimes happen is that, as we become more familiar with the card, we naturally gravitate toward the same types of hands. As a result, it's easy to overlook other possibilities that the tiles may offer, making it feel as though we're being dealt the same hands repeatedly.
If you'd like to broaden your hand recognition, I recommend spending some time in the Exercise Room (under the Play menu). The exercises are designed to improve your knowledge of the card and help you spot a wider range of playable hands from the same set of tiles.