Mortgagee should choose one of the two rights to exercise when the claim of additional mortgage reencountered with the right of subrogation in another thing.

• 增担保请求权与物上代位权发生竞合时,抵押权人得择一行使;在增担保请求权不能实现时,抵押权人得要求债务人提前清偿债务;