Actually, there is a difference. :) In the first sentence you'd have to use the reflexive pronoun twice. It is perfectly fine, because the first "se" is a part of the verb that is conjugated (snažit se -> snažím se; it is therefore in the 2nd position in a sentence, as you know it) and the 2nd "se" is a part of the infinitive "učit se". I try to learn. Snažím se učit se. I try to teach. Snažím se učit.