Because drummers cannot always hold a note to its correct value, as most other instruments can, it is essential for beginners to treat the second note of the tie as a rest, and not to play it.
Here are some examples:
In Example (A) think of the 1st half of the 3rd beat as a rest. In Example (B) think of the 1st half of the 4th beat as a rest. In Example (C) think of the 1st half of beats 2,3,4 as rest.