"I always played sports."
Translation:Yo siempre practiqué deportes.
The first time I encountered this, it was a dictation and Duo said "practiqué'. I typed that but thought that it really should be in the imperfect because of siempre. The next time this came up it was an English-to-Spanish translation exercise so I decided to try the imperfect, "practicaba" and that was accepted (as you said) but Duo gave the preterit as an alternate answer. I'm no expert but I'd probably choose the imperfect because of the word siempre which implies a repeated action in the past.