Key uniqueness

[Hariprasad Govindarajan]

I came across a problem in this link 

[https://leetcode.com/problems/contains-duplicate/][1].

There is an input array of integers. I need to find out if there any repeating integers, then return true else false.

I tried using uthash and my code below works and got accepted. But I got few questions and someone please clarify me:

struct hash {
            int key;
            int value;
            UT_hash_handle hh;
        };
       
        struct hash *hashtable = NULL;
   
        void addToHash(int key, int value)
        {
          struct hash *map;
          //I am using the array elements as hash keys
          HASH_FIND_INT(hashtable, &key, map);
       
          if(map == NULL)
          {
            map = (struct hash*)malloc(sizeof(struct hash));
            map->key = key;
            HASH_ADD_INT(hashtable, key, map);
          }    
          map->value = value;
       }  
   
   
        struct hash *findInHash(int key)
        {
            struct hash *h;
            HASH_FIND_INT(hashtable, &key, h);
            return h;
        }
       
        bool containsDuplicate(int* nums, int numsSize) {
               
            struct hash *hPtr;
            int target = 0;
            hashtable = NULL;
            if((numsSize <= 1) || (nums == 0)) return false;
           
            int i, index1 = 0;  
           
            for(i = 0; i < numsSize; i++)
            {
                /*The below statement will look if the key is already present in the
                  hashtable*/
                hPtr = findInHash(*(nums + i) - target);
                /*If the key is found already, then it look for the value of that
                key. If the value and the current array element is same, then a
                duplicate exist*/
                if(hPtr && hPtr->key == *(nums+i))
                   return true;
                addToHash(*(nums + i), i);
            }
            struct hash *temp;
            HASH_ITER(hh, hashtable, hPtr, temp) {free(hPtr);}
            return false;
        }

In my code above,there is an if conditionif(hPtr && hPtr->key == *(nums+i)). I am using the array elements as keys. If so, each key can't be unique if the same element is repeated twice right? So can I modify the if condition as if(hPtr->key == *(nums + i))? 

If any other mistakes, please feel free to point out.

Thanks

G Hariprasad