This is more than likely due to my lack of reading enough Japanese; however, in this sentence the particles と and に are placed together which I haven't seen before.
Sentence:
一時は観光と買い物とに集中していた外国旅行ツアーも近頃はもっと細かくなって、音楽を聴く旅、城をまわる旅というようにある趣味の目的を持つ旅行計画もできてきた。
Is there an underlying reason for the と in this sentence? Would the sentence be the same with removing the second と?