Diversity antenna and 800MHz gain

Q1: For the Diversity LTE antenna port, can I just connect a separate “LTE Full Band PCB Antenna – u.FL Plug – 100mm”, if this same antenna type is used on the Main LTE port? Or should the diversity antenna be different in some way?

Q2: For the mentioned antenna, what is the RX/TX gain at the B20 band (800MHz)?