Fread read wrong number of valid bytes C

Question

I read two ppm images and I have a struct that stores all the informations (magic number, width, height, level of colors, and pixels). I read the pixels using fread, but the problem is that we have some test to run to see if our code is valid and can create a new ppm. One test must be not valid (not creating an image because the number of pixels is different from the size given), but my code create the image anyway, because in the fread the successful bytes read must be 83 (the condition to exit from the code is that if the number of bytes is different from the given size (width * height * 3) we return 1 and stop executing), but actually it reads 84 bytes, that is equal to the size, then it continue to execute the code, instead of blocking it, and I don't understand why. The error is after the read pixel comment. P.s Because the code works giving two images, I give the same invalid image twice.

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

struct image
{
    char *magicNumber;
    int width;
    int height;
    int level;
    uint8_t *pixels;
};

int main(int argc, char *argv[])
{
    struct image img1;
    struct image img2;
    struct image img3;

    // Read files
    FILE *file1 = fopen(argv[1], "r");
    FILE *file2 = fopen(argv[2], "r");

    // Check files
    if (!file1 || !file2)
    {
        fprintf(stderr, "Error while opening the file.\n");
        return 1;
    }

    // Alloc memory for pixels array
    img1.magicNumber = (char *)malloc(3 * sizeof(char));
    img2.magicNumber = (char *)malloc(3 * sizeof(char));

    // Take magic number
    fscanf(file1, "%s", img1.magicNumber);
    fscanf(file2, "%s", img2.magicNumber);

    // Check magic number
    if (strcmp(img1.magicNumber, "P6") != 0 || strcmp(img2.magicNumber, "P6") != 0)
    {
        fprintf(stderr, "Invalid magic number.\n");
        return 1;
    }
    // Take width
    fscanf(file1, "%d", &img1.width);
    fscanf(file2, "%d", &img2.width);
    // Take height
    fscanf(file1, "%d", &img1.height);
    fscanf(file2, "%d", &img2.height);

    // Check size
    if (img1.width != img2.width || img1.height != img2.height)
    {
        fprintf(stderr, "Invalid Dimension.");
        return 1;
    }
    // Take level
    fscanf(file1, "%d", &img1.level);
    fscanf(file2, "%d", &img2.level);

    // Check level
    if (img1.level != 255 || img2.level != 255)
    {
        fprintf(stderr, "Invalid Level.");
        return 1;
    }
    // Alloc memory for pixels array
    img1.pixels = (uint8_t *)malloc(img1.width * img1.height * 3 * sizeof(uint8_t));
    img2.pixels = (uint8_t *)malloc(img2.width * img2.height * 3 * sizeof(uint8_t));

    // Read pixels
    size_t nrPixel1 = fread(img1.pixels, sizeof(uint8_t), img1.width * img1.height * 3, file1);
    size_t nrPixel2 = fread(img2.pixels, sizeof(uint8_t), img2.width * img2.height * 3, file2);

    // Check pixels read
    if (nrPixel1 != img1.width * img1.height * 3 || nrPixel2 != img2.width * img2.height * 3)
    {
        fprintf(stderr, "Invalid pixels.");
        return 1;
    }