Tigers are found both in Asia and in Africa.
Tigers are found both in Asia and Africa.
I could use in twice in this sentence. Can I omit it the second time?
Tigers are found both in Asia and in Africa.
Tigers are found both in Asia and Africa.
I could use in twice in this sentence. Can I omit it the second time?
Both are correct. If the objects (Africa and Asia) of the prepositions can use the same preposition (in), you may use the preposition once and combine the objects for simplicity. You may, but you are not required to.
To my ear, it sounds better to move the "both" in the combined case, though:
Tigers are found both in Asia and in Africa.
Tigers are found in both Asia and Africa.