Trouble using makefile with multiple files in C

Starting to get my head around makefiles for my C programs, but having some trouble when trying to include multiple files. Ignoring the fact that the program below is incomplete (in terms of functionality but not compilation), I'm trying to get this program compiling and running using a make file.

Here is my make file:

main: main.o IntList.o
    gcc -o main main.o IntList.o

main.o: main.c
    gcc -c -ansi -pedantic -Wall main.c

IntList.o: IntList.c IntList.h
    gcc -c -ansi -pedantic -Wall Intlist.c

And here is the error I am receiving:

gcc -c -ansi -pedantic -Wall Intlist.c
gcc -o main main.o IntList.o
ld: duplicate symbol _getNewInt in IntList.o and main.o
collect2: ld returned 1 exit status
make: *** [main] Error 1

The code for the program is below. I'm not sure whether it's the make file or my includes in the program files that are causing problems (or both!)

Any help would be great. Cheers.

Edit: Any tips to steer me in the right direction in terms of modularization would be much appreciated as I'm not sure if I am doing this the best way.

IntList.h

#include <stdio.h>
    #include <stdlib.h>
    #include <string.h>

/* Constants */
#define MAX_INTS 10

/* Signed ints can have a maximum of 10 digits. We make the length 11 to 
 * allow for the sign in negative numbers */
#define MAX_INPUT_LENGTH 11
#define EXTRA_SPACES 2

/* Typedefs / Structs */
typedef struct {
   int list[MAX_INTS];
   int noInts;
} IntList;

/* Proto Types */
int insertIntToList(int *list);
void shiftList(int offset);
void displayList();

IntList.c

#include "IntList.h"

int getNewInt(int *list)
{
   int valid = 0, inputInt;
   char inputString[MAX_INPUT_LENGTH + EXTRA_SPACES];

   while(!valid)
   {
      printf("Input an int: ");

      valid = 1;

      if((fgets(inputString, MAX_INPUT_LENGTH + EXTRA_SPACES, stdin)) != NULL)
      {
         sscanf(inputString, "%d", &inputInt);
         /* Check first that the input string is not too long */
         if(inputString[strlen(inputString) - 1] != '\n')
         {
            printf("\nError: Too many characters entered \n");
            valid = 0;
         }

         printf("\nThe Int: %d", inputInt);
         printf("\n");
      }
   }
}

void shiftList(int offset)
{
}

void displayList()
{
}

main.c

#include <stdio.h>
#include <stdlib.h>
#include "IntList.c"

int main(void)
{
   int intList[10];

   getNewInt(intList);

   return EXIT_SUCCESS;
}

Don't include the .c file in main, include the .h file. Otherwise the code in IntList.c gets compiled both into the IntList.o and the main.o, so you'll get duplicate symbols.

Use this in main.c instead of IntList.c:

#include "IntList.h"