This might be the reason why university had asked a early deposit for the 2nd semester. Lots of Nepalese came to that university in past years and they transferred to the other colleges next semester. They wanna make sure your brother stays next semester with the same school. That might be the reason they are asking for the early deposit for next semester. If your brother is coming to these states - Oklahoma, Louisiana, mississippi; this must be it.

Other Scenario: If your brother has other I-20s, he can definitely go to other school as well. I paid my sevis fee to X university, applied to Y university and transfered to Z university and graduated from A university. So , everything is possible.

Good luck.