Effect of a translation on cross correlation

Hello,

To find displacement of a particle, I calculated the cross correlation between two instants (represented by two images with the same size). Then, I padded the images with zeros to see if a translation will have an effect on the displacement. Thus I found a difference in displacement vector( the difference can reach 1.5 pixel and the size of image is 56x56 pixels)

Is it normal to find a difference after padding?

N.B: To pad the image, I used

new_image(end+1:56,end+1:56)=0;

Thank you in advance

EDIT

The difference can even be more (22 px)