他比我游得快。他比我游泳游得快。
Both mean : He swims faster than me. NO PROBLEM .
The second sentence is just more repetitive and clearer.
I say it is " repetitive" because when we say " 游" , every Chinese knows it refers to " 游泳" , not nessasary to say " 游泳" again.
When I say the second is clearer , I mean that type of sentence is clearer than the first type when it comes to some other phrases .
eg: 她比我跳得好。She 跳 better than me.
她比我跳绳跳得好。 She jumpes rope better than me.
In my first sentence , I didn't tell what she jumps better than me . but in the second sentence you know I mean JUMP ROPE, not jump high exersise, not 跳舞 either 。
跳舞=dance
她跳得比我好。 VS 她跳舞跳得比我好。 ( The first 跳 is vague , the second is clearly talking about 跳舞。)
One more thing , when you need to say something like this all of a suddenly without any context . You'd better be repetitive , that makes your idea clearly expressed.