array of boost dynamic_bitset. If arr[0][0] bit is set, arr[1][0]test() is also set

I have initialized array of dynamic bitset as follows std::vectorboost::dynamic_bitset<> v =std::vectorboost::dynamic_bitset<>(8, boost::dynamic_bitset<>(2));

I have set v[0].set(0) but v[1].test(0) return true. If I set v[0][0] = 1, automatically other array 0th index bit is also considering as set.

I have set v[0].set(0) but v[1].test(0) return false.